Prediction of Cancer Incidence and Mortality in Korea, 2014
Article information
Abstract
Purpose
We studied and reported on cancer incidence and mortality rates as projected for the year 2014 in order to estimate Korea's current cancer burden.
Materials and Methods
Cancer incidence data from 1999 to 2011 were obtained from the Korea National Cancer Incidence Database, and cancer mortality data from 1993 to 2012 were acquired from Statistics Korea. Cancer incidence in 2014 was projected by fitting a linear regression model to observed age-specific cancer incidence rates against observed years, then multiplying the projected age-specific rates by the age-specific population. For cancer mortality, a similar procedure was employed, except that a Joinpoint regression model was used to determine at which year the linear trend changed significantly.
Results
A total of 265,813 new cancer cases and 74,981 cancer deaths are expected to occur in Korea in 2014. Further, the crude incidence rate per 100,000 of all sites combined will likely reach 524.7 and the age-standardized incidence rate, 338.5. Meanwhile, the crude mortality rate of all sites combined and age-standardized rate are projected to be 148.0 and 84.6, respectively. Given the rapid rise in prostate cancer cases, it is anticipated to be the fourth most frequently occurring cancer site in men for the first time.
Conclusion
Cancer has become the most prominent public health concern in Korea, and as the population ages, the nation's cancer burden will continue to increase.
Introduction
As the leading cause of death in Korea [1], cancer has been the country's major public health concern since 1983. Over 200,000 patients were newly diagnosed with cancer in Korea, and one in four deaths is due to cancer [2]. To plan and implement comprehensive cancer control programs, it is important to estimate, in advance, the number of new cancer cases and deaths that could occur over the following year. Although the cancer registration system in Korea is very efficient and can provide nationwide cancer statistics within a relatively short time, a lag time of at least 2 years is required to collect, compile, and analyze the data on a specific year. In this study, however, we drew on relevant national data from the 1990s through 2012 to forecast the country's cancer incidence and mortality rates for the year 2014 in advance.
Materials and Methods
The Korean Ministry of Health and Welfare initiated a nationwide, hospital-based cancer registry, the Korea Central Cancer Registry (KCCR), in 1980. The history, objectives, and activities of the KCCR have been documented in detail elsewhere [3]. Incidence data from 1999 to 2011 were obtained for analyses from the Korea National Cancer Incidence Database (KNCI DB). Cancer cases were classified according to the International Classification of Diseases for Oncology, 3rd edition [4], and converted according to the International Classification of Diseases, 10th edition (ICD-10) [5]. Mortality data from 1993 to 2012 were acquired from Statistics Korea [1]. The cause of death was coded and classified according to ICD-10 [5].
The cancer sites included in this study were 1) all cancers combined and 2) the 24 common cancers: lip, oral cavity, and pharynx (C00-C14), esophagus (C15), stomach (C16), colon and rectum (C18-C20), liver and intrahepatic bile duct (liver) (C22), gallbladder and other parts of the biliary tract (gallbladder) (C23-C24), pancreas (C25), larynx (C32), lung and bronchus (lung) (C33-C34), breast (C50), cervix uteri (C53), corpus uteri (C54), ovary (C56), prostate (C61), testis (C62), kidney (C64), bladder (C67), brain and central nervous system (C70-C72), thyroid (C73), Hodgkin lymphoma (C81), non-Hodgkin lymphoma (C82-C85, C96), multiple myeloma (C90), leukemia (C91-C95), and others.
Population data for 1993-2013 were obtained from the resident registration population, reported by Statistics Korea. Data on the mid-year population, as of July 1 of the respective year, were analyzed. For the year 2014, however, we used population data as of December 31, 2013, because mid-2014 resident registration population data were not yet available at the time of analysis.
Due to the time required for data collection, compilation, quality control, and analysis, incidence and mortality data for a specific year are usually available 2-3 years later. Therefore, we attempted to project, ahead of 2014, the expected number of new cancer cases and deaths in Korea for the year so as to provide an estimate of the nation's current cancer burden. Linear regression models [6] were used to assess time trends and projections. Based on observed cancer incidence data, a linear regression model was fitted to age-specific rates by 5-year age groups against observed years. The estimated number of new cancer cases was calculated from the projected age-specific rates for 2014, by multiplying the rates by the projected 2014 age-specific population size. For thyroid and prostate cancer, which showed significant curvilinear trends, we used a square-root transformation when fitting a linear regression model and converted the predicted values back to the original scale.
To predict the cancer mortality rate in 2014, we first performed a Joinpoint regression analysis on the data available for 1993-2012 to detect the year when significant changes occurred in cancer mortality trends according to sex and cancer site. A Joinpoint regression describes changes in data trends by connecting several different line segments on a log scale at "joinpoint." This analysis was performed using the Joinpoint software (ver. 4.0; http://surveillance.cancer.gov/joinpoint) from the Surveillance Research Program of the US National Cancer Institute [7].
After identifying the year during which significant trend changes occurred through Joinpoint regression analysis, a simple linear regression model was fitted to the last line segment to estimate age-specific cancer mortality rates in 2014. Similar to the method used for the projection of cancer incidence, the number of new deaths in 2014 was then forecasted by multiplying age-specific cancer mortality rates by the corresponding year's age-specific population.
We summarized the results by using crude rates (CRs) and age-standardized rates (ASRs) of cancer incidence and mortality. ASRs were standardized using the world standard population [8] and expressed per 100,000 persons.
Results
1. Incidence
A total of 265,813 new cancer cases are anticipated in 2014 (Table 1, Fig. 1), with slightly more female (n=134,358) than male (n=131,455) cancer patients expected in the coming year.
The CRs per 100,000 of all sites combined in 2014 are projected to be 519.0 and 530.4 in men and women, respectively. Meanwhile, projected ASRs per 100,000 of all sites combined are 358.4 and 338.3, respectively (Table 2). In men, the five leading primary sites of cancer are expected to be the stomach (CR, 92.7; ASR, 62.7), colon and rectum (CR, 88.1; ASR, 60.1), lung (CR, 67.7; ASR, 45.6), prostate (CR, 53.9; ASR, 36.9), and liver (CR, 50.0; ASR, 33.6), accounting for 67.9% of all newly diagnosed cancers in 2014. Prostate cancer is projected to be the fourth most common cancer site in men for the first time. In women, the five leading primary sites are expected to be the thyroid (CR, 195.8; ASR, 138.3), breast (CR, 72.6; ASR, 48.5), colon and rectum (CR, 54.6; ASR, 30.5), stomach (CR, 43.5; ASR, 24.8), and lung (CR, 29.8; ASR, 15.6), accounting for 74.7% of all newly diagnosed cancers (Fig. 1). Thyroid cancer alone is projected to account for approximately 36.9% (49,604 cases) of incident cases in women in 2014.
The five most common cancer sites expected in 2014 by sex and age group are shown in Table 3. Leukemia and thyroid cancer are expected to be the most common forms of cancer in both genders for the 0-14 and 15-34 age groups. Stomach cancer is predicted to be the most prevalent in men aged 35-64 years, while lung cancer is expected to be more frequent in men aged 65 and over. Thyroid cancer is predicted to be the most common cancer in women 35-64 years of age, whereas colorectal cancer is expected to be the most prevalent in women aged 65 and over. These projections indicate that the incidences of stomach, lung, liver, colorectal and prostate cancers will increase gradually with age. In women, the age-specific incidence rates of colorectal, liver, lung and cervical cancers denote a rising trend in these cancers with age; however, the incidence of breast and thyroid cancer in women is expected to level off after the late 40s and early 50s, respectively (Fig. 2).
2. Mortality
It is estimated that 74,981 cancer deaths will occur in Korea during 2014 (Table 1, Fig. 1). The CRs per 100,000 of all sites combined in 2014 for men and women are projected to be 184.2 and 111.8, respectively, while the ASRs per 100,000 of all sites combined are expected to be 125.7 and 55.3, respectively (Table 4). The five leading cancer sites causing mortality in men are predicted to be lung (CR, 48.7; ASR, 32.7), liver (CR, 31.7; ASR, 21.4), stomach (CR, 20.0; ASR, 13.6), colon and rectum (CR, 19.9; ASR, 13.7), and pancreas (CR, 10.7; ASR, 7.2). During the same time period, lung cancer (CR, 18.3; ASR, 8.5) is projected to be the leading cancer site in women, causing mortality, followed by colon and rectum (CR, 14.6; ASR, 6.7), stomach (CR, 11.1; ASR, 5.2), liver (CR, 10.8; ASR, 5.4), and pancreas (CR, 9.6; ASR, 4.5).
The predicted age-specific mortality rates of the selected cancers for males and females in 2014 are shown in further detail in Fig. 3. When examined by age, Korean men and women aged 60 and over are expected to have the highest mortality rates from lung cancer.
Conclusion
A total of 265,813 new cancer cases and 74,981 cancer deaths are expected to occur in Korea during 2014. In Korean males, stomach, colorectal, lung, prostate, and liver cancers are anticipated to be the most commonly occurring, while lung, liver, stomach, colorectal, and pancreatic cancers are expected to be the most common causes of cancer-related deaths. In Korean women, thyroid, breast, colorectal, stomach, and lung cancers are anticipated to be the most prevalent, while lung, colorectal, stomach, liver, and pancreatic cancers are projected to be the most common causes of cancer-related deaths.
Cancer is, at present, one of the foremost public health concerns in Korea. The country will likely see its cancer burden continue to grow with the aging of its population. The current projections on cancer incidence and mortality for 2014 represent an important resource for planning and evaluating cancer-control programs. As the estimates in this study are model-based, there is a need to exercise caution when using them.
Acknowledgments
This work was supported by a research grant from the National Cancer Center (No. 1310220), Republic of Korea.
Notes
Conflict of interest relevant to this article was not reported.