Adjuvant active specific immunotherapy for human colorectal cancer: 6.5-year median follow-up of a phase III prospectively randomized trial

Abstract

Purpose: Patients with colon or rectal cancer were entered onto a prospectively randomized, controlled clinical trial of active specific immunotherapy (ASI) with an autologous tumor cell-bacillus Calmette-Guérin (BCG) vaccine. We investigated whether ASI could improve disease-free status and survival.

Patients and methods: Ninety-eight patients with Dukes' stage B2-C3 colon or rectal cancer were randomized into groups treated by resection alone or resection plus ASI. Eighty patients met all eligibility criteria. All patients with rectal cancer were to receive 50 Gy of pelvic irradiation. Analysis of distribution of survival and disease-free survival was made on all eligible patients until December 31, 1990.

Results: As a single study, no statistically significant differences were detected in survival or disease-free survival for all 80 eligible patients. However, since it was recognized at the outset that there were treatment differences, in that rectal cancer patients were to receive postimmunotherapy radiation, it was considered that a cohort analysis of the colon and rectal cancer patients might be informative. With a median follow-up of 93 months, there is a significant improvement in survival (two-sided P = .02; hazards ratio, 3.97) and disease-free survival (two-sided P = .039; hazards ratio, 2.67) in all eligible colon cancer patients who received ASI. With a median follow-up of 58 months, no benefits were seen in patients with rectal cancer who received ASI.

Conclusion: This study suggests that ASI may be beneficial to patients with colon cancer.