Cancer Research and Treatment

Original Articles

Early On-Treatment Host Fitness Dynamics Refine Prognostic Stratification in Advanced NSCLC Receiving First-Line Immunotherapy: Se-Il Go, Jinyong Kim, Sehhoon Park, Il Hwan Kim, Dong-Wan Kim, Yun-Gyoo Lee, Jang Ho Cho, Eun Kyung Cho, Hyun Woo Lee, Ji-Hyun Park, Eun Joo Kang, Youngjoo Lee, Nak-Hoon Son, So Hyeon Gwon, Hyun Ae Jung, Jong-Mu Sun, Se-Hoon Lee, Jin Seok Ahn, Myung-Ju Ahn, Gyeong-Won Lee; Received June 7, 2026 Accepted August 7, 2026 Published online August 10, 2026; DOI: https://doi.org/10.4143/crt.2026.0607 [Accepted]

Abstract PDF: Purpose
We assessed whether baseline and early on-treatment measurements of host fitness using the Prognostic Nutritional Index (PNI) provide complementary prognostic information in advanced non-small cell lung cancer (NSCLC).
Materials and Methods
Within the prospective, multicenter OPTIMUS trial, 497 patients with advanced NSCLC receiving first-line pembrolizumab-based therapy were analyzed. PNI was calculated from serum albumin and lymphocyte count at baseline and before cycle 2 (early on-treatment). Using a cutoff of 50.5, 441 patients with paired measurements were classified by baseline/early on-treatment PNI status as high/high, high/low, low/high, or low/low.
Results
Low baseline PNI was associated with lower objective response and higher treatment-related mortality. Among responders, low early on-treatment PNI was associated with lower odds of 6-month response maintenance (adjusted OR, 0.40; 95% CI, 0.17–0.97). Response-maintenance rates were lowest in the low/low group at both 6 and 12 months. In multivariable analyses including both PNI time points, low early on-treatment PNI was associated with shorter PFS (HR, 1.50; 95% CI, 1.11–2.04), whereas low baseline PNI was not (HR, 1.27; 95% CI, 0.94–1.71). Both low baseline PNI (HR, 1.53; 95% CI, 1.07–2.19) and low early on-treatment PNI (HR, 1.47; 95% CI, 1.02–2.12) were associated with shorter OS. The higher mortality risk in the low/low group was generally consistent across PD-L1 expression and treatment regimen subgroups.
Conclusion
PNI assessment at baseline and before cycle 2 provides complementary prognostic information, with early on-treatment PNI particularly related to PFS and response durability (ClinicalTrials.gov Identifier: NCT04909164).

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Impact of Metabolic Syndrome on Risk of Lung Cancer among Korean Never-Smokers: A Nationwide Population-Based Cohort Study: Sung Woo Moon, Jiyeong Kim, Dong-Woo Han, Dong Won Park; Received January 31, 2026 Accepted July 29, 2026 Published online July 30, 2026; DOI: https://doi.org/10.4143/crt.2026.0116 [Accepted]

Abstract PDF: Purpose
To determine the association between metabolic syndrome (MetS) and lung cancer risk in a large population-based cohort of never-smokers in Korea.
Materials and Methods
Using the Korean National Health Insurance Service database, we identified adults who underwent national health screening in 2009 and consistently reported their never-smoker status at baseline and subsequent examinations. Cox proportional hazards models were used to estimate hazard ratios (HRs) for lung cancer incidence, adjusting for age, sex, body mass index (BMI), physical activity, residential area, income, and alcohol consumption. Analyses were further stratified according to sex and BMI.
Results
Overall, 2,721,804 never-smokers were followed up for a mean of 14.0 years. The incidence of lung cancer was higher among participants with MetS than those without (adjusted HR: 1.04, 95% CI: 1.01–1.07). MetS was significantly associated with lung cancer risk in men (HR: 1.18, 95% CI 1.11–1.25) but not in women (HR: 1.03, 95% CI 0.99–1.07), with the risk evident in normal-weight and pre-obese men but, in women, mainly in those with obesity (HR: 1.10, 95% CI 1.03–1.16).
Conclusion
MetS was associated with a modest increase in the risk of lung cancer among Korean never-smokers, showing a significant association among men but not women. MetS risk was evident even among normal-weight men, whereas among women, it was more pronounced in those with obesity. These findings suggest that metabolic abnormalities, relatively underrecognized as cancer-related risk factors, could contribute to the risk of lung cancer, even in the absence of tobacco exposure.

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Pyrotinib Plus Trastuzumab and Docetaxel with Different Antidiarrheal Strategies in Patients with HER2-Positive Recurrent or Metastatic Breast Cancer (PHAENNA): A Multicenter, Phase 1 Trial: Wei Ren, Xiuping Lai, Guiying Bai, Yanqiong Liu, Hongtao Li, Huan Zhou, Shouman Wang, Qun Qin, Wei Li, Cuizhi Geng, Mingxia Wang, Xinshuai Wang, Yu Cao, Zhuang Yu, Caiwen Du, Wei Zhao, Shikai Wu, Yimin Cui, Pan Liu, Kaijing Zhao, Jiaman Lin, Xiaoyu Zhu, Yandan Yao, Yehui Shi, Herui Yao; Received April 12, 2026 Accepted July 14, 2026 Published online July 28, 2026; DOI: https://doi.org/10.4143/crt.2026.0400 [Accepted]

Abstract PDF: Purpose
The outcomes of different antidiarrheal strategies in HER2-positive breast cancer patients treated with pyrotinib plus trastuzumab and docetaxel are unknown.
Materials and Methods
97 eligible patients received pyrotinib once daily from Cycle 1 Day 7 onwards, combined with intravenous trastuzumab and docetaxel on Day 1 of each 21-day cycle. In the 400PYR cohort, patients were treated with 400 mg pyrotinib, without mandatory antidiarrheal prophylaxis. In the 320PYR+Pro-L and 400PYR+Pro-L cohorts, patients were given 320 or 400 mg pyrotinib and loperamide prophylaxis. In the 320PYR cohort, patients were treated with 320 mg pyrotinib, without mandatory antidiarrheal prophylaxis. In the PYR-DE+Pro-L cohort, patients were treated with escalating pyrotinib doses and loperamide prophylaxis.
Results
The incidence of grade 3 diarrhea in cohorts with loperamide prophylaxis was lower than in the 400PYR cohort. In the 3 cohorts with loperamide prophylaxis, the dose escalation cohort had the lowest incidence of grade 3 diarrhea. The incidence of grade 3 diarrhea in 320PYR cohort was similar to the 3 cohorts with prophylactic antidiarrheal loperamide. No event of grade 4 or 5 diarrhea was reported.
Conclusion
Loperamide prophylaxis and pyrotinib dose escalation were associated with lower observed rates of grade 3 diarrhea in patients receiving pyrotinib plus trastuzumab and docetaxel. The lower rate observed in the 320PYR cohort should be interpreted cautiously and may reflect improved clinical management rather than a reproducible protocolized intervention.

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Prevalence and Potential Clinical Relevance of Germline Pathogenic Variants in Korean Biliary Tract Cancer: Jun-Ha Jang, Jong Eun Park, Jung Won Chun, Hyeji Kim, Jinhyuk Bhin, Junghyeok Lim, Sang Myung Woo, Joo Kyung Park, Dae Wook Hwang, Sung-Sik Han, Woo Jin Lee, Dong-Eun Lee, Sang-Jae Park, Sun-Young Kong; Received April 30, 2026 Accepted July 20, 2026 Published online July 21, 2026; DOI: https://doi.org/10.4143/crt.2026.0484 [Accepted]

Abstract PDF: Purpose
This study aimed to identify germline pathogenic/likely pathogenic variants in DNA damage repair genes associated with increased cancer risk in Korean patients with biliary tract cancer and characterize their population-specific patterns.
Materials and Methods
In this retrospective multicenter cohort study, we performed germline whole-exome sequencing in 172 Korean patients diagnosed with intrahepatic cholangiocarcinoma (n = 83) or gallbladder cancer (n = 89) between June 2001 and February 2022. Germline variants were analyzed in 210 hereditary cancer genes, and the germline landscape of this cohort was compared with that of global cohorts.
Results
Pathogenic/likely pathogenic variants were identified in 24 of 172 (14.0%) patients, predominantly in DNA damage repair genes (18 of 24 [75.0%]). BRCA2 was among the most frequently altered genes, harboring two distinct pathogenic variants (2 of 24 [8.3%]; both cases of intrahepatic cholangiocarcinoma). Of the 24 carriers, five (20.8%) harbored Tier 1–2 variants of potential, tumor-confirmation-dependent therapeutic relevance. Notably, 15 of 24 (62.5%) carriers reported no family cancer history. In population-stratified comparisons across nine biliary tract cancer cohorts (n = 4,018), PMS2 showed a Korean-enriched signal after accounting for heterogeneous gene coverage, whereas TP53 showed only a directional, non-significant increase after multiple-testing correction.
Conclusion
The study findings provide reference data for genetic counseling in East Asian patients with biliary tract cancer and suggest that germline testing may warrant consideration regardless of family history.

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A Prognostic Risk Model for Breast Cancer Integrating Migrasome and Tumor Microenvironment Features to Predict Immunological Characteristics: Jingbo Du, Lin Zhu; Received December 30, 2025 Accepted July 13, 2026 Published online July 15, 2026; DOI: https://doi.org/10.4143/crt.2025.1417 [Accepted]

Abstract PDF: Purpose
Breast cancer (BRCA) is a heterogeneous disease with a complex etiology. The prognostic value of genes related to migrasomes and the tumor microenvironment (MTMERGs) in BRCA is unclear.
Materials and Methods
A prognostic risk model was constructed using six core signature genes identified from MTMERGs via differential expression analysis and Cox regression. Its reliability was validated in an independent cohort using Kaplan-Meier and time-dependent ROC curves. A nomogram was developed and assessed via Decision Curve Analysis (DCA). Biological functions and immune infiltration were evaluated with GSEA, CIBERSORT, and ssGSEA. Immunotherapy sensitivity was predicted using TIDE/IPS scores and the IMvigor210 cohort. Tumor Mutation Burden (TMB) analysis and the pRRophetic algorithm were used for further clinical correlation and drug sensitivity prediction.
Results
The six-MTMERG model effectively stratified patients into high- and low-risk groups with distinct survival outcomes. The high-risk group was associated with a predicted immunosuppressive microenvironment (estimated enrichment of M0/M2 macrophages), higher TMB, and poorer prognosis. In contrast, the low-risk group was estimated to possess an immunologically active profile and showed a better predicted response to immune checkpoint inhibitors. Predicted differential sensitivities to conventional chemotherapy were also computationally evaluated between the subgroups.
Conclusion
We developed a computationally derived and externally validated prognostic model for BRCA based on migrasome and tumor microenvironment features. It successfully stratifies patients into groups with divergent clinical outcomes, immune profiles, and therapeutic responses, providing insights into BRCA heterogeneity and prognosis. Further prospective and experimental validation is warranted before clinical application.

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Neutrophil-to-Lymphocyte Ratio and Extrahepatic Spread Predict Response and Survival in Unresectable Hepatocellular Carcinoma: Dong Yun Kim, Heechul Nam, Jun Yong Park, Sang Hoon Ahn, Sung Won Lee, Do Young Kim; Received May 8, 2026 Accepted July 3, 2026 Published online July 7, 2026; DOI: https://doi.org/10.4143/crt.2026.0498 [Accepted]

Abstract PDF: Purpose
Identifying nonresponders to atezolizumab plus bevacizumab (AB) remains challenging in unresectable hepatocellular carcinoma (uHCC). We aimed to develop and externally validate a simple risk scoring system using baseline neutrophil-to-lymphocyte ratio (NLR) and extrahepatic spread (EHS) to predict treatment outcomes.
Materials and Methods
We included 304 patients with uHCC receiving first-line AB from multiple Korean centers (discovery, n = 220; validation, n = 84). Study outcomes included objective response rate (ORR) assessed by modified Response Evaluation Criteria in Solid Tumors, overall survival (OS), and progression-free survival (PFS). Multivariable analysis identified high NLR (>4.575) and EHS as independent predictors of nonresponse. The NLR-EHS score assigned 2 points for high NLR and 1 point for EHS (range, 0–3).
Results
In the discovery cohort, the score predicted nonresponse with an area under the receiver operating characteristic curve (AUC) of 0.749 (95% CI, 0.688–0.810); ORR fell across low- (0), moderate- (1–2), and high-risk (3) groups (67.3%, 47.7%, and 8.2%; p < 0.001). Validation confirmed comparable discrimination (AUC, 0.705; 95% CI, 0.603–0.806) and a consistent ORR gradient (77.8%, 54.2%, and 22.2%; p < 0.001). The score was prognostic for OS in discovery (HR, 1.28; p = 0.003) and validation cohorts (HR, 1.45; p = 0.007), remaining significant after adjustment (adjusted HR, 1.25 and 1.61, respectively). High-risk patients had inferior median OS (6.9 vs. 17.1 months in validation).
Conclusion
The NLR-EHS score is a practical tool for stratifying nonresponse risk and survival in uHCC patients receiving AB, facilitating early identification of high-risk patients who may benefit from alternative strategies.

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Clinico-Pathologic Features of Adult Erdheim–Chester Disease in South Korea: A Multicenter Retrospective Study (KCSG LY22-15): Ji Yun Lee, Heounjeong Go, Myung-won Lee, Ji Hyun Lee, Sang Eun Yoon, Jee Hyun Kong, Sojung Lim, Yoon Kyung Jeon, Tae Min Kim; Received April 14, 2026 Accepted June 22, 2026 Published online June 29, 2026; DOI: https://doi.org/10.4143/crt.2026.0404 [Accepted]

Abstract PDF: Purpose
Erdheim–Chester disease (ECD) is a rare non-Langerhans cell histiocytosis characterized by heterogeneous multisystem manifestations and frequent MAPK–ERK pathway alterations. Data on the clinico-pathologic features and real-world outcomes of adult ECD in South Korea are limited.
Materials and Methods
We conducted a retrospective multicenter cohort study of adult patients (≥18 years) with ECD at seven Korean Cancer Study Group (KCSG)-affiliated institutions between October 2008 and June 2024. Clinical and pathologic features, BRAF V600E mutation status, treatment patterns, and overall survival (OS) were analyzed using the Kaplan–Meier method.
Results
Twenty-two patients were included (median age 57 years [IQR 45–64]; 50% male). Organ involvement was heterogeneous: bone (54.5%), retroperitoneal/renal (31.8%), central nervous system (27.3%), cardiovascular (27.3%), hypothalamic-pituitary axis (27.3%), pulmonary (18.2%), and skin (13.6%); multisystem disease (≥2 organs) was present in 40.9%. BRAF V600E was positive in 11 of 19 tested patients (57.9%). Systemic treatment was initiated in 18 patients (81.8%); interferon-α-based regimens were the most common first-line approach (50.0%). Among 16 evaluable patients, the disease control rate (CR/PR/SD) was 87.5%. With a median follow-up of 4.6 years (IQR 1.3–6.5), 2- and 5-year OS rates were 90.0% and 74.3%, respectively.
Conclusion
Korean adult patients with ECD demonstrate heterogeneous organ involvement and frequent BRAF V600E positivity. Real-world treatment remains dominated by interferon-α-based approaches, underscoring the need for standardized molecular testing and improved access to targeted therapy.

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Individual SGLT-2 Inhibitors and Risk of New-Onset Cancer in Type 2 Diabetes: A Nationwide Population-Based Cohort Study: Hayeon Kim, Jun-ho Seo, Jin Hyun Nam, Yejee Lim, Ji-Won Kim, Boyoon Choi, Suin Kang, Youngjoo Byun, Kyungim Kim; Received November 11, 2025 Accepted June 18, 2026 Published online June 22, 2026; DOI: https://doi.org/10.4143/crt.2025.1243 [Accepted]

Abstract PDF: Purpose
Preclinical studies suggest that sodium-glucose cotransporter-2 inhibitors (SGLT-2is) may have cancer-preventive effects; however, clinical evidence remains inconclusive. Therefore, this study aimed to evaluate the association between the use of SGLT-2is (empagliflozin or dapagliflozin) and the incidence of new-onset cancer in patients with type 2 diabetes.
Materials and Methods
This nationwide retrospective cohort study used Korean national health claims data. Patients with type 2 diabetes who started empagliflozin, dapagliflozin, or other glucose-lowering drugs (oGLDs) between 2016 and 2019 were included, and propensity score matching between the SGLT-2is users and oGLDs users was applied. The primary outcome was overall cancer incidence, and the secondary outcomes were the incidence of 11 site-specific cancers. Hazard ratios (HRs) and confidence intervals (CIs) for cancer incidence adjusted for covariates were estimated using a Cox proportional hazards model.
Results
After propensity score matching, each group comprised 20,456 patients. There was no significant difference in the overall incidence of new-onset cancer in either the empagliflozin or dapagliflozin groups when compared to the oGLDs user group (adjusted HR 0.85, 95% CI 0.65–1.12; adjusted HR 0.87, 95% CI 0.66–1.14, respectively). Similar results were observed in site-specific cancer incidence. Furthermore, there were no significant differences in overall or site-specific cancer incidence between the empagliflozin and dapagliflozin user groups. The results were consistent across subgroup analyses and various sensitivity analyses.
Conclusion
In this large-scale national cohort study, the use of empagliflozin or dapagliflozin did not show a significant difference in the incidence of new-onset cancer in patients with type 2 diabetes. These results provide evidence supporting the association between SGLT-2i use and cancer risk in this population, based on real-world clinical data. Longer-term follow-up studies would be helpful in strengthening the validity of these findings.

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Clinical Effectiveness and Cost-Effectiveness of Robot-Assisted Versus Conventional Esophagectomy: Joon Beom Park, Myung-Il Hahm, Hong Kwan Kim, Danbee Kang, Seong Yong Park; Received October 29, 2025 Accepted June 8, 2026 Published online June 19, 2026; DOI: https://doi.org/10.4143/crt.2025.1188 [Accepted]

Abstract PDF: Purpose
This study evaluated the comparative clinical effectiveness and cost-effectiveness of robot-assisted minimally invasive esophagectomy (RAMIE) versus open esophagectomy (OE) and conventional minimally invasive esophagectomy (MIE) in a nationwide real-world setting.
Materials and Methods
A target trial emulation was conducted using the Korean National Health Insurance Service database, including patients who underwent first-time esophagectomy for esophageal cancer between 2010 and 2023, with survival followed through June 2024. Propensity score–matched cohorts were created for RAMIE versus OE (n=1,713 per group) and RAMIE versus MIE (n=1,162 per group). Clinical outcomes were compared, and a 5-year semi-Markov model was used to estimate quality-adjusted life-years (QALYs) and costs from a healthcare sector perspective with a 4.5% annual discount rate. Incremental cost-effectiveness ratios (ICERs), incremental net benefits (INBs), and probabilistic sensitivity analyses were calculated.
Results
RAMIE showed comparable or better short-term outcomes, including lower incidence of transfusion-requiring bleeding risk than OE (23.6% vs. 32.5%; relative risk [RR], 0.73; 95% CI, 0.65–0.81) and MIE (27.9% vs. 33.6%; RR, 0.88; 95% CI, 0.77–0.99). Long-term survival was superior to OE (hazard ratio [HR], 0.80; 95% confidence interval [CI], 0.72–0.88) and similar to MIE (HR, 0.93; 95% CI, 0.82–1.06). RAMIE yielded higher QALYs (Δ0.311 vs. OE; Δ0.126 vs MIE) and lower 5-year costs ($12,372–$19,765 vs. OE; $1,703–$9,097 vs. MIE), resulting in negative ICERs, positive INBs, and high probabilities of cost-effectiveness in sensitivity analyses.
Conclusion
RAMIE showed a favorable clinical and cost-effectiveness profile compared with OE and MIE, adding to the evidence base for its broader adoption.

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Perceptions and Use of Complementary and Alternative Medicine among Patients with Cancer and Their Family Members (KCSG PC21-19): Young-Woong Won, Sun Young Rha, Jung Hye Kwon, Yu Jung Kim, Shin Hye Yoo, Myung Ah Lee, Jung Hun Kang, Sun Jin Sym, Young Saing Kim, Sang-Cheol Lee, Myung-Won Lee, Hye Sook Han, Sang-Gon Park, Eun-Kee Song, Jin Young Kim, Seong Hoon Shin, Chi Hoon Maeng, Keun Seok Lee, Hyun Woo Lee, Woo Kyun Bae, Kyu-Hyoung Lim, Yoon Jung Chang, Han Byul Lee, Jung Sun Kim; Received November 18, 2025 Accepted June 7, 2026 Published online June 11, 2026; DOI: https://doi.org/10.4143/crt.2025.1251 [Accepted]

Abstract PDF Supplementary Material: Purpose
This study aimed to assess the awareness, perception, and utilization of complementary and alternative medicine (CAM) among Korean patients with cancer and their caregivers. Furthermore, it evaluated CAM information sources, the reliability of these sources, communication patterns with clinicians, and the effect of caregiver beliefs on the use of CAM and patients’ attitudes toward CAM.
Materials and Methods
A nationwide cross-sectional survey was conducted from September 2021 to January 2022 across 19 hospitals in South Korea. Adult patients with cancer and their accompanying caregivers were recruited via convenience sampling from outpatient oncology clinics and inpatient settings and completed a structured questionnaire. Data from 1,804 patients and 768 family members were analyzed using descriptive statistics and appropriate comparative tests.
Results
Among patients, 47.2% had heard of CAM, and 41.0% expressed belief in it. Biologically based therapies were the most commonly used form of CAM among users (55.0%). The primary sources of CAM information were family/relatives (24.8%) and television (23.8%), whereas medical professionals accounted for only 5.4% of sources, although doctors and nurses were perceived as the most reliable (mean reliability: 3.43 on a 5-point scale). A significant communication gap was observed, with 71.7% of patients not discussing CAM with their medical professionals. Common reasons for non-disclosure included a lack of patient interest (39.4% of non-disclosers), the perception that CAM was irrelevant to their doctors (27.6%), and concerns about physician disapproval. Among patients who did consult their clinicians, 60.8% were advised against CAM use. Caregivers’ CAM beliefs significantly influenced patients’ beliefs (odds ratio [OR], 4.242; p<0.001), although this did not translate into a statistically significant direct effect on CAM use by patients (OR, 1.449; p=0.105).
Conclusion
CAM awareness and use are substantial among Korean patients with cancer; however, a critical communication gap with healthcare providers persists. Family members are key information sources, and caregiver beliefs influence patient beliefs regarding CAM. Proactive, empathetic, and evidence-based communication about CAM is essential to promote shared decision-making and ensure safe, patient-centered integrative cancer care.

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Spatial Disparities in Stage-Specific Breast Cancer Incidence and Area-Level Risk Factors in Korea, 2005–2018: Eun Hye Park, Kyu-Won Jung, Seung-sik Hwang, So-Youn Jung, Jae Kwan Jun; Received November 19, 2025 Accepted June 5, 2026 Published online June 8, 2026; DOI: https://doi.org/10.4143/crt.2025.1268 [Accepted]

Abstract PDF: Purpose
Despite a nationwide breast cancer screening program in Korea, spatial disparities in stage at diagnosis persist. This study aimed to examine disparities in breast cancer incidence by stage and their association with area-level risk factors.
Materials and Methods
We conducted a population-based ecological study using data from the Korea National Cancer Incidence Database (2005–2018). Among 230,214 women diagnosed with breast cancer, 215,803 with known stage were included. Stage-specific incidence across 250 municipalities was estimated for three periods (2005–2008, 2009–2013, and 2014–2018). For 2014–2018, associations with the area deprivation index (ADI), obesity rate, alcohol consumption rate, cancer screening rate, and mammography unit availability were assessed using Bayesian hierarchical models.
Results
Of 215,803 patients, 59.0% had localized-stage, 35.5% regional-stage, and 5.5% distant-stage. Localized-stage incidence was higher in affluent areas, whereas distant-stage incidence was higher in deprived areas. In multivariable models, lower ADI (β = -0.058; 95% credible interval [CrI]: -0.098, -0.019), lower obesity rate (β=-0.066; 95% CrI: -0.091, -0.041), and higher mammography availability (β=0.014; 95% CrI: 0.001, 0.027) were significantly associated with higher localized-stage incidence. Conversely, higher ADI (β=0.103; 95% CrI: 0.017, 0.188) and higher alcohol consumption (β=0.227; 95% CrI: 0.115, 0.338) were significantly associated with increased distant-stage incidence.
Conclusion
Spatial disparities in stage-specific breast cancer incidence in Korea were associated with area-level deprivation, healthcare resources, and health-related behaviors. Integrating spatial perspectives into cancer control strategies may help promote more equitable early detection and contribute to improve breast cancer outcomes.

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Distinct Evolutionary Dynamics of HER2-Ultralow Versus HER2-Null from Residual to Metastatic Disease in Non-pCR Breast Cancer: Shunan Wang, Jingjing Liu, Tong Liu, Shichao Zhang, Xinyu Liu, Yu Liu, Jin Zhang; Received March 22, 2026 Accepted May 11, 2026 Published online May 12, 2026; DOI: https://doi.org/10.4143/crt.2026.0302 [Accepted]

Abstract PDF: Purpose
In breast cancer (BC) patients without pathological complete response (pCR) after neoadjuvant therapy, residual disease drives recurrence. The HER2 spectrum now includes HER2-low and HER2-ultralow. HER2-low tumors are eligible for HER2-targeted antibody-drug conjugates (ADCs), while T-DXd is approved for HR-positive HER2-ultralow metastatic BC after endocrine therapy. Evolution patterns of HER2-ultralow versus HER2-null from residual to metastatic disease remain unclear.
Materials and Methods
We retrospectively studied 488 non-pCR patients with refined HER2 classification; 92 with HER2-0 residual disease formed the analytic cohort for HER2-ultralow/HER2-null comparison. HER2 status was tested in paired residual and metastatic lesions. Logistic regression was used to identify factors linked to HER2 evolution.
Results
In the 92‑patient HER2‑0 analytic cohort, HER2-ultralow (46.7% of HER2-0) converted more frequently to HER2-low than HER2-null (51.2% vs 30.6%, p=0.045). This difference remained statistically significant in the multivariable logistic regression model. In the full 517-patient contextual cohort, HER2 expression gain in recurrent/metastatic lesions was independently associated with poorer post-recurrence survival (PRS) (adjusted HR=1.74, p=0.009). In the 488-patient primary cohort, conversion from HER2-0 to HER2-low was also associated with poorer PRS (adjusted HR=2.18, p<0.001). The broader HER2 expression evolution in the full 517‑patient cohort and the primary 488‑patient refined HER2 cohort was consistent with the core finding from the 92‑patient HER2‑0 analytic cohort and supported its biological plausibility.
Conclusion
HER2-ultralow shows distinct evolution and high HER2-low conversion potential, affecting ADC eligibility. Routine HER2-0 subclassification and metastatic HER2 reassessment appear clinically useful and warrant prospective validation.

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Genetic Variant at 6p21.1 Impairs APOBEC2 in Hypoxic Mitophagy via HIF-1α/BNIP3 in Gastric Cancer: Zhonghua Zheng, Qian Li, Yuanliang Gu, Xinxiang Gao, Xinya Wang, Yan Zhang, Fangmei An, Qiang Zhan, Shuangshuang Yin, Yun Gao, Rui Peng, Li Liu, Erbao Zhang, Meng Zhu, Xiaofeng Chen, Gang Li, Hao Xu, Guangfu Jin, Caiwang Yan; Received October 30, 2025 Accepted May 8, 2026 Published online May 12, 2026; DOI: https://doi.org/10.4143/crt.2025.1194 [Accepted]

Abstract PDF: Purpose
Genome-wide association studies (GWASs) have identified single-nucleotide polymorphisms (SNPs) at the 6p21.1 locus associated with gastric cancer (GC) risk. However, the underlying biological mechanisms remain poorly understood.
Materials and Methods
We conducted fine-mapping analysis of the 6p21.1 region using large-scale GC GWAS data (10,254 cases and 10,914 controls). Functional annotation, luciferase reporter assays, Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) experiments were performed to identify functional variants. The eQTL and colocalization analyses were used to determine the susceptibility gene. Mechanistic investigations included phenotypic assays under normoxic and hypoxic conditions, along with seahorse, immunofluorescence and ATP assays to assess mitochondrial function.
Results
We identified rs9381024 as the independent association signal at 6p21.1, with rs2235679, in strong linkage disequilibrium with rs9381024, emerging as a potential causative SNP. The T risk allele of rs2235679 reduced APOBEC2 expression by enhancing the binding of transcriptional repressor MZF1, thereby suppressing promoter activity. Expression analysis revealed a progressive decrease in APOBEC2 levels with gastric lesions severity, becoming nearly undetectable in GC tissues. Functionally, reduced APOBEC2 expression significantly promoted the proliferation of GC cells under hypoxic conditions but not under normoxia. Mechanistically, downregulation of APOBEC2 activated mitophagy to maintain mitochondria homeostasis via HIF-1α/BNIP3 pathway under hypoxia, ultimately driving tumor growth.
Conclusion
Our findings provide novel mechanistic insights into how genetic variants at 6p21.1 contribute to GC risk and progression, highlighting the tumor-suppressive role of APOBEC2.

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Gaps between Supportive Care Needs and Services in Korea: Experiences and Preferences of Patients with Advanced Cancer and Their Caregivers in the Hospital and at Home: Min Seol Jang, In Gyu Hwang, Shin Hye Yoo, Belong Cho, Bhumsuk Keam, Yu Jung Kim, Sun Kyung Baek, Min Sun Kim, Sun Young Lee; Received October 23, 2025 Accepted May 4, 2026 Published online May 7, 2026; DOI: https://doi.org/10.4143/crt.2025.1162 [Accepted]

Abstract PDF: Purpose
With longer survivals in advanced cancer, the need for supportive care is increasing. However, in Korea, these services remain limited, and many patients rely on long-term care hospitals. We investigated the supportive care experiences of patients with advanced cancer and their caregivers, and preferred place of care (pPOC) by performance status (PS).
Materials and Methods
A cross-sectional survey was conducted at a tertiary hospital in Seoul, Korea, targeting patients hospitalized only for supportive care and their caregivers. PS was assessed using the Eastern Cooperative Oncology Group scale [good (0–1) or poor (2–4)]. Hospital and home care experiences and pPOC were compared by PS. Logistic regression analysis was used to identify factors associated with pPOC.
Results
This study included 200 participants (117 patients, 83 caregivers). Among patients, 72% had good PS and 28% had poor PS. Main reasons for hospitalization were symptom control (51.2%), assistance with daily living (36.5%), and device or wound management (22.5%). Overall, 60.5% of participants reported discomfort during hospitalization, mostly related to hospital life, and 34.5% noted that care was insufficient at home, particularly those in the poor PS group (27.1% vs. 53.6%). Concern about emergencies was the most common home-care difficulty. Despite these challenges, 60% of participants chose home as their future pPOC, with no significant differences by PS or other demographic/clinical factors.
Conclusion
Although most patients with advanced cancer and their caregivers preferred home for supportive care, many relied on hospitals. Structured home-based medical care programs are urgently required in South Korea.

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A Phase Ib/II Study of Pemigatinib in Combination with Paclitaxel in Patients with Gastric Cancer with FGFs/FGFRs Alterations: Minkyu Jung, Soo Hyun Park, Hyoyoung Kim, Youhyun Kim, Un-Jung Yun, Jiwoo Hwang, Hyo Song Kim, Choong-kun Lee, Hyunki Kim, Chung Lee, Dong-Hoe Koo, Hei-Cheul Jeung, Dae Young Zang, Eun-Kee Song, Sun Young Rha; Received December 10, 2025 Accepted May 1, 2026 Published online May 4, 2026; DOI: https://doi.org/10.4143/crt.2025.1352 [Accepted]

Abstract PDF: Purpose
Pemigatinib is a selective inhibitor of fibroblast growth factor receptors (FGFR) 1–3 with demonstrated activity in tumors harboring FGFR2 fusions or amplifications. This phase Ib/II trial assessed the efficacy and safety of pemigatinib in combination with paclitaxel in patients with recurrent or advanced gastric cancer exhibiting FGFs/FGFRs alterations.
Materials and Methods
Patients with gastric cancer harboring FGFs/FGFRs aberrations who experienced progression following first-line therapy were enrolled. The phase Ib component established the recommended phase II dose (RP2D); the phase II component evaluated clinical efficacy.
Results
Twelve patients were enrolled. The RP2D was determined as pemigatinib 13.5 mg/day (days 1–21) plus paclitaxel 80 mg/m² (days 1, 8, 15) every 4 weeks. Median progression-free and overall survival were 4.4 and 10.5 months, respectively. Patients with FGFR2 amplification (n=6) exhibited prolonged progression-free survival (6.5 vs. 3.5 months, p=0.049), while overall survival did not differ significantly. The objective response and disease control rates were 33.3% and 91.7%, respectively. The most frequent treatment-related adverse events were neutropenia (83.3%, grade ≥3: 58.3%) and hyperphosphatemia (83.3%, grade ≥3: 33.3%).
Conclusion
Pemigatinib plus paclitaxel demonstrated antitumor activity with an acceptable safety profile in FGFR2-amplified gastric cancer. Further investigation is warranted to elucidate resistance mechanisms and validate these findings in larger cohorts.

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Is Adjuvant Chemotherapy Necessary for All Patients with pT3N0 Rectal Cancer after Upfront Surgery? A Multicenter Retrospective Study: Kyong-Min Kang, Ho Yung Lee, Hong-min Ahn, Heung-Kwon Oh, Duck-Woo Kim, Sung-Bum Kang, Dong Woon Lee, Sung Chan Park, Jae Hwan Oh, Min Jung Kim, Ji Won Park, Seung-Bum Ryoo, Seung-Yong Jeong, Kyu Joo Park; Received November 27, 2025 Accepted April 30, 2026 Published online May 4, 2026; DOI: https://doi.org/10.4143/crt.2025.1308 [Accepted]

Abstract PDF: Purpose
The role of adjuvant chemotherapy (ACT) in pathologic T3N0 (pT3N0) rectal cancer, which has a favorable prognosis, remains controversial because high-risk groups for recurrence are not well defined. This study investigated prognostic factors for survival in this patient group and evaluated the benefit of ACT based on these factors.
Materials and Methods
This retrospective study analyzed 352 patients with pT3N0 rectal cancer who underwent upfront radical surgery at three referral hospitals between November 2003 and December 2020. A multivariable Cox regression model was used to identify the prognostic factors for 5-year recurrence-free survival (RFS). Patients were categorized as high or low risk based on these factors, and survival outcomes were compared between those who received ACT and those who did not, using the log-rank test.
Results
Median follow-up was 52.8 months. 193 (54.8%) patients received ACT. Multivariable analysis revealed that ACT, circumferential resection margin (CRM) ≤ 2mm, vascular invasion, and perineural invasion were independent predictors of 5-year RFS. In patients with ≥ 1 risk factor, ACT significantly improved RFS (92.5% vs. 72.8%, hazard ratio [HR] 0.247, 95% confidence interval [CI] 0.090–0.683, p < 0.01). In those without risk factors, no significant benefit was observed (98.0% vs. 91.6%, HR 0.272, 95% CI 0.057–1.313, p=0.082).
Conclusion
This study identified CRM ≤ 2mm, vascular invasion, and perineural invasion as high-risk features for recurrence in pT3N0 rectal cancer. ACT improved RFS only in patients with these features. While these findings support risk-based ACT administration in this patient population, further validation of our risk stratification system is needed.

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Concurrent Chemoradiotherapy with or without Induction Chemoimmunotherapy in Unresectable Esophageal Squamous Cell Carcinoma: A Multicenter Real-World Study: Biqi Chen, Peiying Cen, Qi Cheng, Tiejun Wang, Zimeng Li, Chen Yi, Xingyuan Cheng, Dongmei Chi, Shiliang Liu, Yujia Zhu, Hao Zhang, Mian Xi, Baoqing Chen, Yujin Xu, Qiaoqiao Li; Received November 7, 2025 Accepted April 27, 2026 Published online April 28, 2026; DOI: https://doi.org/10.4143/crt.2025.1224 [Accepted]

Abstract PDF: Purpose
This study aimed to compare the efficacy and safety of concurrent chemoradiotherapy (CCRT) with or without induction chemoimmunotherapy (CI) in unresectable esophageal squamous cell carcinoma (ESCC).
Materials and Methods
The study included patients with unresectable ESCC who received CCRT with or without induction CI at three cancer centers. Patients receiving concurrent immunotherapy were excluded. Propensity score matching (PSM) balanced baseline characteristics between groups.
Results
A total of 519 patients were included. After PSM, 183 patients per group were selected. Induction CI significantly improved OS and PFS compared to CCRT alone, consistently. The median OS for CCRT and induction CI groups were 29.9 months (95% CI: 18.8-41.0) and not reached (HR: 0.57, 95% CI: 0.42-0.77, p < 0.001). The median PFS was 17.6 months (IQR: 13.7-21.4) versus 30.6 months (IQR: 17.3-43.8) (HR: 0.66, 95% CI: 0.51-0.86, p = 0.002). Responders to the induction CI had significantly better OS (HR: 0.22, 95%CI: 0.14-0.36, p < 0.001) than nonresponders. Subgroup analysis showed radiation dose escalation or consolidation immunotherapy did not further improve survival in the induction CI group.
Conclusion
The addition of induction chemoimmunotherapy to CCRT was associated with improved survival in patients with locally advanced unresectable ESCC, particularly in responders to induction chemoimmunotherapy, with acceptable toxicity. These findings warrant confirmation in prospective randomized trials.

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Review Article

Toward Sustainable Care in HER2-Positive Metastatic Breast Cancer: Emerging Evidence for Treatment De-escalation: Matilda Xinwei Lee, Soo Chin Lee; Cancer Res Treat. 2026;58(3):697-708. Published online April 23, 2026; DOI: https://doi.org/10.4143/crt.2025.1131

Abstract PDF PubReader ePub: Major advances in the management of human epidermal growth factor receptor 2 (HER2)–positive (HER2+) metastatic breast cancer (MBC) have been achieved through treatment intensification with novel HER2-targeted agents and combination strategies, resulting in substantial survival gains. However, indefinite exposure to systemic therapy imposes cumulative toxicity, financial strain, and quality-of-life burdens. In contrast, the concept of treatment de-escalation, aimed at maintaining disease control with less intensive therapy, has only recently emerged as a complementary paradigm. This review highlights two evolving avenues of treatment de-escalation. First, in hormone receptor–positive/HER2+ disease, randomized trials have demonstrated that combining HER2 blockade with endocrine therapy and cyclin-dependent kinase 4 and 6 inhibitors can overcome endocrine resistance, offering a chemotherapy-sparing approach with outcomes comparable to chemotherapy or antibody-drug conjugates. Second, in long-term responders, retrospective analyses and ongoing prospective trials are evaluating whether discontinuation of prolonged maintenance HER2 therapy can safely reduce treatment burden while preserving disease control, with the added potential for effective rechallenge upon relapse. Together, these developments suggest that treatment de-escalation represents a rational and necessary treatment strategy. Future progress will depend on biomarker-driven patient selection and prospective validation. Redefining success in HER2+ MBC to include not only survival but also quality of life and sustainability represents an important step toward patient-centered cancer care.

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Original Article

Is Complete Mesocolic Excision with Central Vascular Ligation Necessary for Suspected Early-stage Right-sided Colon Cancer?: Mi Jeong Choi, Duck-Woo Kim, Yu Kyung Jun, Ji Ae Lee, Jeehye Lee, Hong-Min Ahn, Heung-Kwon Oh, Sung-Bum Kang; Received September 29, 2025 Accepted April 13, 2026 Published online April 15, 2026; DOI: https://doi.org/10.4143/crt.2025.1065 [Accepted]

Abstract PDF: Purpose
To assess lymph node status in patients undergoing additional surgery after endoscopic resection to evaluate the need for complete mesocolic excision with central vascular ligation for clinically suspected early-stage right-sided colon cancer.
Materials and Methods
This retrospective study, conducted at a single institution using a prospectively collected database, comprised patients who underwent additional surgery following endoscopic intervention between May 2003 and March 2022. The primary outcomes were the rate and location of lymph node metastases, including peritumoral, pericolic, and superior mesenteric lymph nodes. The secondary outcome was recurrence-free survival.
Results
Among 119 patients, pathological examination identified 5 (4.2%) with Tis requiring surgery owing to uncheckable margins or tumor depth, 106 (89.1%) with stage T1 tumors, and 8 (6.7%) with stage T2 tumors. The nodal stage was N0 in 107 patients (89.9%) and N1 in 12 (10.1%) patients. The mean number of harvested lymph nodes was 39.7, including 7.6 ± 6.9 peritumoral, 31.5 ± 14.4 pericolic, and 4.0 ± 3.8 superior mesenteric nodes. All metastatic lymph nodes were in the peritumoral and pericolic regions. At a mean follow-up of 48.2 months, recurrence occurred in one (0.8%) patient, who developed liver metastases 24 months postoperatively.
Conclusion
For patients with clinically suspected early-stage right-sided colon cancer who initially underwent endoscopic resection, the risk of superior mesenteric node metastases is very low. D2 lymph node dissection alone may be sufficient rather than routine application of complete mesocolic excision with central vascular ligation, which might be reconsidered in these patients.

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Special Articles

Cancer Statistics in Korea: Incidence, Mortality, Survival, and Prevalence in 2023: Eun Hye Park, Kyu-Won Jung, Seo Hyun Choi, Nam Ju Park, Mee Joo Kang, E Hwa Yun, Hye-Jin Kim, Jeong-Eun Kim, Kui Son Choi, Han-Kwang Yang, The Community of Population-Based Regional Cancer Registries; Cancer Res Treat. 2026;58(2):349-367. Published online March 23, 2026; DOI: https://doi.org/10.4143/crt.2026.298

Abstract PDF Supplementary Material PubReader ePub

Purpose
The current study provides national cancer statistics and their secular trends in Korea, including incidence, mortality, survival, and prevalence in 2023, with international comparisons.
Materials and Methods
Cancer incidence, survival, and prevalence rates were calculated using the Korea National Cancer Incidence Database (1999-2023), with survival follow-up until December 31, 2024. Mortality data were obtained from the Ministry of Data and Statistics, while international comparisons were based on GLOBOCAN data.
Results
In 2023, 288,613 newly diagnosed cancer cases (age-standardized rate [ASR], 288.6 per 100,000) and 85,271 deaths from cancer (ASR, 64.3 per 100,000) were reported. Among the incident cases, 145,452 (50.4%) were aged 65 years or older. Prostate cancer became the most common cancer among men for the first time. The proportion of localized-stage cancers increased from 45.6% in 2005 to 51.8% in 2023. Korea had the lowest cancer mortality among countries with similar incidence rates and the lowest mortality-to-incidence ratios for stomach, colorectal, and breast cancer. The 5-year relative survival rate (2019-2023) was 73.7% overall and 92.7% for localized-stage cancers. Over 2.73 million prevalent cases were identified in 2023, representing 5.3% of the Korean population.
Conclusion
These findings indicate that Korea’s cancer control efforts have contributed to early detection and improved survival outcomes. As Korea enters a super-aged society in 2025, cancer burden will continue to increase, requiring sustained and adaptive cancer control strategies.

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Epidemiological Trends, Inter-Cancer Correlations, and Incidence Projections for 61 Cancer Types in Korea, 1999–2028: A Nationwide Population-Based Study
Hyeran Jung, Minsun Jung
Cancers.2026; 18(14): 2341. CrossRef
Single-port robotic areolar surgery for thyroid and neck procedures: a 3-year, 500-case single-surgeon experience using the da-Vinci SP system
Myeong Ho Shin, Gi Tae Kim, Seung Hwan Lim, Jin Wook Yi
Updates in Surgery.2026;[Epub] CrossRef
Shifting Cancer Landscapes in Korea: Divergent Incidence Trajectories, Sex-Specific Burdens, and Projected Case Counts for 24 Major Cancer Types from 1999 to 2023, with Forecasts to 2030
Hyeran Jung, Minsun Jung
Current Oncology.2026; 33(8): 444. CrossRef

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Prediction of Cancer Incidence and Mortality in Korea, 2026: Kyu-Won Jung, Mee Joo Kang, Eun Hye Park, E Hwa Yun, Hye-Jin Kim, Jeong-Eun Kim, Kui Sun Choi, Han-Kwang Yang; Cancer Res Treat. 2026;58(2):368-375. Published online March 23, 2026; DOI: https://doi.org/10.4143/crt.2026.289

Abstract PDF PubReader ePub

Purpose
This study aimed to project cancer incidence and mortality for 2026 to estimate Korea’s current cancer burden.
Materials and Methods
Cancer incidence data from 1999 to 2023 were obtained from the Korea National Cancer Incidence Database, while cancer mortality data from 1993 to 2024 were acquired from the Ministry of Data and Statistics. Cancer incidence and mortality were projected by fitting a linear regression model to observed age-specific cancer rates against their respective years and then by the projected age-specific rates by the anticipated age-specific population for 2026. A joinpoint regression model was applied to identify significant changes in trends, using only the most recent trend data for predictions.
Results
A total of 308,876 new cancer cases and 86,317 cancer deaths are expected in Korea in 2026. The most commonly diagnosed cancer is projected to be thyroid cancer, followed by the colorectal, lung, breast, prostate and stomach cancers. These six cancers are expected to account for 63.5% of all newly diagnosed cancers. Lung cancer is expected to be the leading cause of cancer-related deaths, followed by liver, colorectal, pancreatic, gallbladder, and stomach cancers, together comprising 65.9% of all cancer deaths.
Conclusion
Korea’s cancer burden continues to shift toward malignancies prevalent in older populations. The sustained increase in prostate cancer among men and the rising mortality impact of pancreatic cancer reflect structural changes in the national cancer profile amid rapid population aging.

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Longitudinal Analysis of Testicular Cancer Patient Volume and Co-Occurring Urological Conditions Using the Health Insurance Review and Assessment (HIRA) Database in South Korea (2020–2024) with Exploratory Forecasts for 2026–2028
Hyeran Jung, Minsun Jung
Cancers.2026; 18(14): 2325. CrossRef

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Original Articles

Spatial Interactions of CD103+ Tissue-Resident Memory T Cells in the Tumor Periphery Are Associated with Clinical Outcomes in Triple-Negative Breast Cancer Following Neoadjuvant Chemotherapy: Hyun Lee, Byung-Kwan Jeong, Gyungyub Gong, Miseon Lee, Hee Jin Lee; Received December 29, 2025 Accepted March 15, 2026 Published online March 17, 2026; DOI: https://doi.org/10.4143/crt.2025.1416 [Epub ahead of print]

Abstract PDF Supplementary Material: Purpose
Triple-negative breast cancer (TNBC) is an aggressive subtype with poor prognosis. CD103+ tissue-resident memory T cells are crucial for anti-tumor immunity in TNBC. We investigated whether their spatial interactions with other T-cells influence clinical outcomes, particularly following neoadjuvant chemotherapy (NAC).
Materials and Methods
This retrospective study analyzed 182 TNBC patients (98 NAC-treated, 84 non-NAC). Using Opal multiplex immunohistochemistry data and the Spatial Image Analysis of Tissues R package, we analyzed spatial interactions between CD103+ cells and other T-cell subsets (CD45RO, CD8, CD4, and programmed cell death 1) in central/peripheral tumor regions. Normalized mixing score (NMS) quantified spatial interactions.
Results
NMS-based clustering revealed two distinct CD103+ cell interaction patterns—cluster 1 (low NMS) characterized by weaker and cluster 2 (high NMS) by stronger spatial interactions between CD103+ and other T-cell subsets. In the NAC group, cluster 2 in the tumor periphery was associated with lower pathologic stage (p=0.002), higher stromal tumor-infiltrating lymphocyte level (p=0.031), and significantly improved recurrence-free survival (p=0.028) and overall survival (p=0.018) compared to cluster 1. Central tumor region clustering patterns had no association with prognosis. No significant survival-related differences were observed in the non-NAC group according to NMS-based clustering.
Conclusion
Spatial interaction patterns between CD103+ and other T-cell subsets in the tumor periphery influence clinical outcomes in NAC-treated TNBC patients. Analysing such spatial relationships between T cells, rather than their presence alone, may provide additional prognostic information for patients undergoing NAC.

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Gastrointestinal cancer

Korean Colorectal Cancer Screening Guidelines for Asymptomatic, Average-Risk Adults: The 2025 Revision: EunKyo Kang, Jae Myung Cha, Seo Young Kang, Kiheon Lee, Su Young Kim, Younghoon Kim, An Na Seo, Hyo-Jin Kang, Jong Keon Jang, Kwang-Pil Ko, Aesun Shin, Dae Kyung Sohn, Youngki Hong, Eun-Jung Cho, Minje Han, Soo Young Kim, Hyeon Ji Lee, Chang Kyun Choi, Mina Suh; Cancer Res Treat. 2026;58(3):872-883. Published online March 13, 2026; DOI: https://doi.org/10.4143/crt.2026.014

Abstract PDF Supplementary Material PubReader ePub

Purpose
This study aimed to develop the 2025 update to the Korean colorectal cancer (CRC) screening guidelines by systematically assessing recent evidence, integrating domestic data, and addressing changes since the 2015 guideline revision, and accordingly, provide an evidence-based standard for clinicians and policymakers.
Materials and Methods
A multidisciplinary committee developed the guidelines using the Grading of Recommendations, Assessment, Development and Evaluation methodology. The process involved establishing three key questions focused on efficacy, accuracy, and optimal age and interval for screening. A systematic review of international guidelines and primary literature (327 studies included) was conducted. A utility-based analysis using the Markov model was also performed to determine optimal screening ages and intervals.
Results
The review identified high-certainty evidence for fecal immunochemical test (FIT) in reducing CRC mortality and moderatecertainty evidence for colonoscopy. Evidence for computed tomography colonography (CTC) and stool DNA testing showed very low certainty. Based on this synthesis and cost-utility analysis, the committee conditionally recommends screening for asymptomatic, average-risk adults aged 45-74 years using either colonoscopy every 10 years or FIT every 1-2 years. CTC and stool DNA testing were not recommended owing to insufficient evidence.
Conclusion
The 2025 Korean Guidelines for Colorectal Cancer Screening provide the latest evidence-based recommendations tailored to the domestic context. By conditionally adopting both colonoscopy and FIT for individuals aged 45-74 years, these guidelines aim to optimize public health outcomes and reduce the colorectal cancer burden in South Korea.

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Age-dependent effects of gastric cancer screening endoscopy on mortality: a nationwide cohort study
Seokho Myeong, Jaehun Jung, Ki-Hwan Bae, Ilsoo Kim, Donghoon Kang, Yu Kyung Cho, Hyeon Woo Yim, Jae Myung Park
Endoscopy.2026;[Epub] CrossRef

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Conditional Relative Survival and Competing Mortality in Surgically Treated Patients with Localized and Regional Kidney Cancer in Korea: A Nationwide Cohort Study: Hyun Bin Shin, Dong Wook Shin, In Young Cho, Junhee Park, Jin Hyung Jung, Kyungdo Han, Jinsung Park; Received May 24, 2025 Accepted March 5, 2026 Published online March 9, 2026; DOI: https://doi.org/10.4143/crt.2025.557 [Epub ahead of print]

Abstract PDF Supplementary Material: Purpose
This study aimed to investigate the 5-year conditional relative survival and competing mortality in surgically treated patients with localized and regional kidney cancer.
Materials and Methods
Using a nationwide population-based database, the Korea Clinical Data Utilization Network for Research Excellence, conditional relative survival conditioned on 1 to 3 years of survival after diagnosis was measured. These rates were stratified by age, sex, socioeconomic status, comorbidities, and treatment received. Cause of death and estimated cause-specific mortality were also described and considered with competing risks.
Results
This study included a total of 19,749 newly diagnosed patients with kidney cancer who underwent surgical treatment from 2013 to 2019. The baseline conditional relative survival rates for the entire cohort, patients with localized disease, and patients with regional disease were 97.2%, 99.4%, and 82.6%, respectively. After 1 year, these rates increased to 99.3%, 99.5%, and 97.1%, respectively. Patients who underwent surgery only had the highest baseline conditional relative survival rates (99.3%) compared with those who received surgery with radiotherapy (74.0%), with chemotherapy (38.9%), and with chemotherapy and radiotherapy (16.2%). Specifically, patients who underwent robotic surgery or partial nephrectomy showed higher baseline conditional relative survival rates (> 100%) than others. Furthermore, kidney cancer was the leading cause of death (49.6%), followed by other types of cancer and cardiovascular disease. Over time, kidney cancer-specific mortality decreased.
Conclusion
Conditional survival after surgery for localized or regional kidney cancer was high and improved over time. These findings indicate that long-term prognosis varies by stage and patient characteristics and should inform postoperative surveillance.

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Effect of Smoking Cessation Duration on Lung Cancer Incidence: A Nationwide Retrospective Cohort Study in Korea: Myeong Geun Choi, Min-Ho Kim, Hong Jin Kim, Eun Mi Chun; Received October 10, 2025 Accepted February 25, 2026 Published online February 26, 2026; DOI: https://doi.org/10.4143/crt.2025.1099 [Epub ahead of print]

Abstract PDF Supplementary Material: Purpose
While smoking cessation is known to reduce lung cancer risk, the extent to which smoking cessation duration mitigates lung cancer risk remains unclear. This study aimed to analyze the association between smoking cessation duration and the reduction in lung cancer incidence using large-scale health insurance data from Korea.
Materials and Methods
In this retrospective cohort study, we utilized the cohort from the Korea National Health Insurance Corporation. Approximately 50% of the adults aged ≥ 50 years who underwent health examinations in 2009-2013 were randomly sampled and followed using medical and health examination records. The participants were classified into three groups: never-smokers, former smokers, and current smokers, and the incidence rates of lung cancer were compared among these groups.
Results
We analyzed 165,512 individuals selected through propensity score matching (82,756 never-smokers, 41,378 former smokers, and 41,378 current smokers). Lung cancer risk significantly decreased after 2 years of smoking cessation (2-3 years after cessation: hazard ratio, 0.760; p < 0.001) but remained higher than that of never-smokers for up to 10 years. Subgroup analyses revealed similar tendencies among males, whereas no consistent patterns were observed among females. Moreover, a longer duration of smoking cessation was generally required for heavy smokers (≥ 20 pack-years) than for light smokers (< 20 pack-years).
Conclusion
This nationwide cohort study highlights the significant impact of smoking cessation duration on lung cancer risk, emphasizing the substantial benefits of even short-term cessation regardless of prior smoking history.

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Assessing Radiation Pneumonitis through Functional Lung Imaging: A Single Photon Emission Computed Tomography–Based Approach in Lung Cancer: Joo-Hyun Chung, Soo Jin Lee, Ji Young Kim, Hae Jin Park; Received November 13, 2025 Accepted February 18, 2026 Published online February 19, 2026; DOI: https://doi.org/10.4143/crt.2025.1248 [Epub ahead of print]

Abstract PDF Supplementary Material: Purpose
This study aimed to develop models to assess the risk of symptomatic radiation pneumonitis (SRP) (Common Terminology Criteria for Adverse Events ver. 4.03 grade ≥ 2) in lung cancer patients by utilizing single-photon emission computed tomography (SPECT) for functional lung volume identification and dosimetric analysis.
Materials and Methods
This retrospective study included 71 lung cancer patients who underwent SPECT before radiotherapy from 2018 to 2024. Perfusion and ventilation SPECT images were co-registered with planning computed tomography to define functional and anatomical lung volumes. Functional lung was defined as voxels with ≥ 20% of the maximum intensity on SPECT. Models to assess the risk of SRP were constructed using Cox regression and evaluated using corrected Akaike information criterion (AICc) and time-dependent receiver operating characteristic analysis.
Results
At a median follow-up of 16.8 months, 19 of 71 patients (26.8%) developed SRP. Factors significantly associated with SRP risk included planning target volume ≥ 150 mL, percentage of total perfusion-defined functional lung receiving ≥ 10 Gy (pVf10) exceeding that of total anatomical lung receiving ≥ 10 Gy (V10), percentage of total ventilation-defined lung receiving ≥ 10 Gy (vVf10) ≥ 45%, and ipsilateral vVf10 ≥ 60% (p=0.004, p=0.004, p=0.024, and p=0.007, respectively). Among the three models, the model incorporating additional ventilation-based parameters demonstrated the best performance (AICc, 85.81; area under the curve, 0.819).
Conclusion
SPECT-based dosimetric parameters derived from perfusion and ventilation are significantly associated with the risk of SRP. Incorporating SPECT may improve risk stratification and enable lung-sparing strategies.

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A Phase I/II Trial to Evaluate the Safety and Efficacy of Continuous Positive Airway Pressure in Volumetric Modulated Arc Therapy for Breast Cancer: Jung Bin Park, Tosol Yu, Jaeman Son, Chul-Won Choi, Seho Kwon, Hyun-Woo Shin, Hak Jae Kim, Ji Hyun Chang; Received November 22, 2025 Accepted January 25, 2026 Published online January 26, 2026; DOI: https://doi.org/10.4143/crt.2025.1281 [Epub ahead of print]

Abstract PDF PubReader ePub: Purpose
This phase I/II study aimed to evaluate the tolerability and the organ-sparing effects of continuous positive airway pressure (CPAP) in breast cancer radiotherapy (RT).
Materials and Methods
We conducted a prospective, single-institutional trial approved by the Ministry of Food and Drug Safety of South Korea. Patients with breast cancer who received postoperative RT underwent 4D-CT simulation and treatment planning under both free breathing (FB) and CPAP-assisted breathing (WC), with a target pressure of 20 cm H₂O. Adverse events (AEs) were evaluated, and dosimetric parameters of organs at risk and heart position change were compared between the FB and WC arms.
Results
Among 20 enrolled patients, four withdrew due to discomfort during simulation. During the trial, no CPAP-related AEs of grade 2 or higher were observed. Compared to FB, CPAP reduced the mean heart dose by 34.7% (p < 0.001), as well as V₅-V₃₀ for both the left ventricle and left anterior descending artery (all p < 0.05). It also led to significant reductions in V5-V40 and the mean ipsilateral lung dose, including a 4.4% reduction in V20 (all p < 0.001). The heart centroid shifted rightward (4.8 mm), ventrally (8.1 mm), and caudally (16.3 mm) with CPAP, displacing the heart away from the RT field.
Conclusion
CPAP demonstrated both safety and efficacy for breast cancer RT, achieving significant reductions in cardiac and pulmonary radiation exposure. These findings support further investigation of CPAP as a novel respiratory motion management strategy. Future studies are warranted to identify optimal CPAP pressure levels to facilitate broader clinical implementation.

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Salidroside-Loaded, TMTP1-Modified Cancer Stem Cell–Derived Exosomes Reprogram the PI3K/AKT/mTOR Axis to Overcome PD-1 Resistance in Breast Cancer: Faxiang Yin, Xin Jin, Ligong Zhang, Qiang Xie, Jun Qian; Received August 8, 2025 Accepted January 11, 2026 Published online January 14, 2026; DOI: https://doi.org/10.4143/crt.2025.849 [Epub ahead of print]

Abstract PDF Supplementary Material PubReader ePub: Purpose
This study aimed to elucidate how salidroside-loaded, oligopeptide-modified tumor exosomes (Salidroside@T-exo) rewire the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) axis to remodel the immune microenvironment and reverse acquired programmed cell death-1 (PD-1) resistance in breast cancer.
Materials and Methods
Cancer stem cell (CSC)–derived exosomes were surface-engineered with TMTP1 peptide and electroporated with salidroside. PD-1–resistant MA782/5s-8101-R cells and an orthotopic mouse model were used. Multi-omics, flow cytometry, enzyme-linked immunosorbent assay, immunofluorescence, in vivo imaging, and molecular assays examined immune and signaling outcomes.
Results
Salidroside@T-exo restored T-cell interferon γ (IFN-γ) and granzyme B secretion, suppressed CD8+ T-cell apoptosis, and inhibited p-PI3K/p-AKT/p-mTOR in T cells. CSC migration, invasion, and stemness (OCT4, NANOG, and SOX2) were markedly reduced. Tumor growth, Ki-67 index, and CSC frequency dropped while terminal deoxynucleotidyl transferase dUTP nick end labeling–positive cells rose.
Conclusion
Salidroside@T-exo reverses PD-1 blockade resistance by simultaneously inhibiting PI3K/AKT/mTOR signaling in T cells and eradicating breast CSCs, offering a clinically translatable strategy for refractory breast cancer immunotherapy.

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Radiomics-Based Prediction of Lymphedema after Radiotherapy in Breast Cancer: Integrating Clinical and Dosimetric Features: Jae Sik Kim, Seung Hyuck Jeon, Bum-Sup Jang, Jin Ho Kim, Ji Hyun Chang, Dowook Kim, Kyung Hwan Shin; Received September 9, 2025 Accepted January 11, 2026 Published online January 13, 2026; DOI: https://doi.org/10.4143/crt.2025.985 [Epub ahead of print]

Abstract PDF Supplementary Material PubReader ePub: Purpose
Arm lymphedema is a common, debilitating complication in patients with breast cancer undergoing postoperative radiotherapy (PORT). Although clinical and dosimetric factors have been used for risk prediction, radiomics offers a novel approach for improving the predictive accuracy.
Materials and Methods
We designed a predictive model for lymphedema using clinical, dosimetric, and radiomic features. We included 532 patients (399 training and 133 testing) who underwent breast cancer surgery followed by PORT. Radiomic features were extracted from axillary levels I, II, III, and supraclavicular regions, which were automatically contoured on PORT-planning computed tomography scans. Least absolute shrinkage and selection operator regression was used for feature selection. Model performance was evaluated using the area under the curve (AUC), accuracy, sensitivity, and specificity.
Results
The combined model integrating clinical, dosimetric, and radiomic features showed higher predictive performance (AUC: training 0.783, test 0.767, total 0.779) than the clinical/dosimetric (AUC: training 0.730, test 0.671, total 0.717) and radiomics-only (AUC: training 0.721, test 0.668, total 0.708) models. The combined model also achieved a higher accuracy (training 78.9%, test 78.2%, total 78.8%), sensitivity (training 74.6%, test 62.5%, total 72.0%), and specificity (training 79.7%, test 80.3%, total 79.9%) than the other models. DeLong’s test confirmed that the combined model significantly outperformed the clinical/dosimetric model (p=0.036 in training and p=0.010 in all datasets).
Conclusion
Integrating radiomic features with clinical and dosimetric factors showed potential to enhance lymphedema prediction in patients with breast cancer receiving PORT. This model can potentially guide personalized treatment strategies and improve patient outcomes.

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Unplanned Readmission among Patients with Advanced Cancer on Active Treatment: Multi-center, Retrospective Study: Sun Young Lee, Hong Jun Kim, Shin Hye Yoo, In Gyu Hwang, Beodeul Kang, Yu Jung Kim, Dalyong Kim, Chung Ryul Oh, Sun Kyung Baek, Eun Hee Jung, Go-Un Woo, Woohyeon Cho, In Young Hwang, Kyae Hyung Kim, Min Sun Kim, Belong Cho; Received March 19, 2025 Accepted December 30, 2025 Published online January 2, 2026; DOI: https://doi.org/10.4143/crt.2025.330 [Epub ahead of print]

Abstract PDF Supplementary Material PubReader ePub: Purpose
Unplanned readmissions of patients with cancer increase healthcare costs and disrupt care. Although well-studied in surgical oncology, data on patients receiving active treatment for advanced cancer remain limited. This study examined the causes, clinical characteristics, and outcomes of unplanned readmissions.
Materials and Methods
This retrospective, multicenter study included patients with advanced solid tumors from six South Korean university hospitals who had unplanned readmissions within 1 month of prior hospitalization in 2019. Patients with terminal cancer who did not receive active treatment were excluded. Readmissions were categorized as cancer progression (e.g., worsening symptoms), treatment-related (e.g., therapy complications), or other (e.g., non-cancer conditions). Additional unplanned hospital use within 1 month post-discharge was analyzed in survivors with 6-month follow-up data.
Results
Among the 542 patients, readmissions were classified as cancer progression (42.6%), treatment-related (37.3%), or other (20.1%). The cancer progression group had the longest hospital stay (median, 12 days) and the highest mortality (23.4%). The treatment-related group had shorter stays (8 days) and lower mortality (8.4%). Among the 445 survivors, 24.9% had unplanned hospital visits within 1-month post-discharge. Home discharge increased the likelihood of these events (adjusted odds ratio: 4.82 for readmissions, 2.65 for emergency department visits).
Conclusion
Cancer progression was the leading cause of readmission and was associated with prolonged hospital stays and high mortality rates. Home discharge is a key predictor of early additional unplanned hospital visits, indicating the need for careful post-discharge monitoring in this population.

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