Adverse events of postoperative adjuvant chemotherapy predict survival outcomes in locally advanced colorectal cancer: a pooled analysis of Japanese clinical trials

Adverse events during postoperative adjuvant chemotherapy may reflect prognosis in resectable advanced colorectal cancer. This study assessed the association between these events and survival in advanced colorectal cancer patients. We analysed patient data from four Japanese randomised controlled trials on adjuvant chemotherapy for stage II or III colorectal cancer. Adverse events were defined as the maximum grade within 6 months. The primary outcome was overall survival, analysed using a multivariate-adjusted Cox proportional hazard model. A total of 4,046 patients with advanced colorectal cancer undergoing adjuvant chemotherapy were included. Maximum adverse event grades were: 739 (18%) grade 0, 960 (24%) grade 1, 1511 (37%) grade 2, 779 (19%) grade 3 and 57 (1.4%) grade 4. Compared to grade 0, hazard ratios for overall survival were 0.77 (95% CI, 0.61–0.98) for grade 1, 0.70 (95% CI, 0.56–0.87) for grade 2, 0.69 (95% CI, 0.53–0.91) for grade 3 and 1.12 (95% CI, 0.62–2.04) for grade 4. The severity of adverse events during adjuvant chemotherapy correlated with survival outcomes in advanced colorectal cancer. Mild to moderate events were linked to improved prognosis, while absence suggested poorer outcomes, indicating a need for alternative treatments.