Comparison of adverse events during 5‐fluorouracil versus 5‐fluorouracil/oxaliplatin adjuvant chemotherapy for stage III colon cancer

BACKGROUND: In clinical trials, combined 5‐fluorouracil (5FU) plus oxaliplatin improves the survival of patients who have resected, stage III colon cancer with manageable toxicity. However, the tolerability of this in the general population of patients with colon cancer is uncertain. METHODS: Adverse outcomes were compared in patients with stage III colon cancer who received either 5FU or 5FU/oxaliplatin within 120 days of undergoing resection versus a control group of patients with stage II colon cancer who did not receive chemotherapy in the Surveillance, Epidemiology, and End Results (SEER)‐Medicare database and in data from the New York State Cancer Registry linked to Medicare and Medicaid. Hospitalizations, emergency room (ER) visits, and outpatient adverse events (AEs) were measured in claims from 30 days to 9 months after patients underwent resection. Multiple logistic regression was used to calculate adjusted odds ratios of events by treatment. Propensity score matching was used to minimize selection bias. RESULTS: Adverse outcomes were more frequent for chemotherapy recipients. AE rates were higher in patients who received 5FU/oxaliplatin (81%) compared with patients who received 5FU alone (72%), in the SEER‐Medicare data. The effect of oxaliplatin on AEs was greater in older patients: The odds ratio was 2.10 (95% confidence interval, 1.53‐2.87) for patients aged ≥75 years versus 1.75 (95% confidence interval, 1.39‐2.21) for patients aged