For patients with Dukes' stage B and C rectal cancer, surgery followed by adjuvant chemoradiotherapy is considered to be the standard treatment. However, the drugs used in combination with 5-fluorouracil (5-FU), the method of administration, duration of adjuvant therapy and the frequencies of administration presently remain controversial topics. We investigated (1) the efficacy and safety of adjuvant radiotherapy and 5-FU/leucovorin (LV) chemotherapy for patients who had undergone curative resection and (2) the effect of dose related factors of 5-FU on survival.

130 rectal cancer patients with Dukes' B or C stage disease who were treated with curative resection were evaluated. The adjuvant therapy consisted of two cycles of 5-FU/LV chemotherapy followed by pelvic radiotherapy with chemotherapy, and then 4~10 more cycles of the same chemotherapy regimen were delivered based on the disease stage. The cumulative dose of 5-FU per body square meter (BSA), actual dose intensity and relative dose intensity were obtained. The patients were divided into two groups according to the median value of each factor, and the patients' survival rates were compared.

With a median follow-up duration of 52 months, the 5-year disease-free survival and overall survival rates of 130 patients were 57% and 73%, respectively. Locoregional failure occurred in 17 (13%) of the 130 patients, and the distant failure rate was 27% (35/130). The chemotherapy related morbidity was minimal, and there was no mortality for these patients. The cumulative dose of 5-FU/BSA had a significant effect on the 5-year overall survival for Dukes' C rectal cancer patients (p=0.03). Multivariate analysis demonstrated that only the performance status affected the 5-year overall survival (p=0.003).

An adjuvant therapy of radiotherapy and 5-FU/LV chemotherapy is effective and tolerable for Dukes' B and C rectal cancer patients. A prospective, multicenter, randomized study to evaluate the effects of the cumulative dose of 5-FU/BSA on survival is required.