Effect of adjuvant chemo- or immunotherapy on the prognosis of colorectal cancer operated for cure

Abstract

After radical surgery for colorectal cancer, 178 patients with a Dukes' B or C tumour were randomly assigned to one of three groups: A, controls (n = 62); B, chemotherapy (n = 59); C, immunotherapy (n = 57). Randomization criteria (age, sex, Dukes' stage, localization of tumour, operative procedure) were evenly distributed throughout the groups. After a median observation time of 30 months, statistical analyses were performed: survival and probability to be free of recurrence was described by Kaplan-Meier estimates of the survival function; for comparison of these survival functions, Breslow's test was used. Overall analyses show no benefit in the treatment group compared to controls. Separate analyses by Dukes' stages showed that in patients with Dukes' C tumours the probability of survival 40 months after surgery was 72 per cent in group C, 51 per cent in group B, and 33 per cent in group A. The differences between groups C and A, and B and A were statistically significant (P less than 0.02 and P less than 0.03 respectively). For a Dukes' C tumour the probability to be free of distant metastases at 30 months after surgery was 80 per cent in group B, 68 per cent in group C and 52 per cent in group A. Also for a Dukes' C tumour the probability to be free of liver metastases at 21 months after surgery was 83 per cent in group B, 81 per cent in group C, and 54 per cent in group A (significant differences: B-A and C-A P less than 0.04 for both). There was no influence on the estimated incidence of local recurrences for stage Dukes' C. Patients with a Dukes' B tumour did not benefit from either of the adjuvant therapy schemes.