Radiation therapy and fluorouracil with or without semustine for the treatment of patients with surgical adjuvant adenocarcinoma of the rectum. Gastrointestinal Tumor Study Group

Abstract

Purpose: To evaluate the contribution of semustine (MeCCNU) to adjuvant benefit, previously untreated patients with histologically proven adenocarcinoma of the rectum who had undergone curative resection were randomized to treatment with combination radiation therapy and fluorouracil (5-FU) followed by either 12 months of 5-FU and MeCCNU or 6 months of escalating 5-FU.

Patients and methods: Between March 1981 and November 1985, 210 patients were randomized by Gastrointestinal Tumor Study Group (GITSG) investigators. Subsequent to randomization, 11 (5%) patients (six treated with 5-FU and MeCCNU; five with escalating 5-FU) were found to be ineligible and are excluded from survival analyses.

Results: About half the patients on each of the two treatment arms experienced at least one episode of severe or worse toxicity, and there was one treatment-related death on each arm. No episodes of leukemia have been reported. Median follow-up time for surviving patients is 5.8 years, and 3-year follow-up is available for all but five surviving patients. Recurrent disease has been reported in 54% (51 of 95) of 5-FU- and MeCCNU-treated patients compared with 43% (45 of 104) of escalating 5-FU-treated patients. Probability of 3-year disease-free survival for the two treatment cohorts is 54% and 68%, respectively. Ninety-one deaths have occurred: 46% (44 of 95) of 5-FU- and MeCCNU-treated patients and 45% (47 of 104) of escalating 5-FU-treated patients. Three-year postsurgery survival probabilities are 66% and 75%.

Conclusion: Substantial differences in survival or recurrence results between the two study arms are unlikely to be observed. We conclude that MeCCNU is not an essential component of effective postoperative combined modality treatment of adjuvant rectal cancer.