Recurrence and cancer-specific death after adjuvant chemotherapy for Stage III colon cancer

The recommended standard of care for patients after resection of Stage III colon cancer is adjuvant 5-fluorouracil based chemotherapy - FOLFOX (fluorouracil, leucovorin with oxaliplatin) - or CAPOX (capecitabine, oxaliplatin). This may be modified in older patients or depending on comorbidity. This has been challenged recently as the apparent benefit of adjuvant chemotherapy may arise from improvements in surgery or preoperative imaging or pathology staging. This study compares recurrence and colon-cancer-specific death between patients who received postoperative adjuvant chemotherapy and those who did not.

Prospectively recorded data from 363 consecutive patients who had a resection for Stage III colonic adenocarcinoma between 1995 and 2010 inclusive were analysed. Surviving patients were followed for at least 5 years. The suitability of patients for chemotherapy was discussed routinely at multidisciplinary team meetings. The incidence of recurrence and colon-cancer-specific death was evaluated by competing risk methods.

After adjustment for the competing risk of non-colorectal cancer death, there was no significant difference in recurrence between the 204 patients who received chemotherapy and the 159 who did not [hazard ratio (HR) 0.94, 95% CI 0.66-1.32, P = 0.700) and no significant difference in colon-cancer-specific death (HR 0.73, 95% CI 0.50-1.04, P = 0.084; HR 0.88, 95% CI 0.57-1.36, P = 0.577 after adjustment for relevant covariates).

These findings question the routine use of chemotherapy after complete mesocolic excision for Stage III colon cancer. Recurrence and cancer-specific death, assessed by competing risk methods, should be the standard outcomes for evaluating the effectiveness of adjuvant chemotherapy after potentially curative resection.