Survival outcomes associated with completion of adjuvant oxaliplatin-based chemotherapy for stage III colon cancer: a national population-based study

Abstract

The impact of cycle completion rates of oxaliplatin-based adjuvant chemotherapy for stage III colon cancer in real-world practice is unknown. We assessed its impact, and that of treatment modification, on 3-year cancer-specific mortality. 4147 patients with pathological stage III colon cancer undergoing major resection from 2014 to 2017 in the English National Health Service were included. Chemotherapy data came from linked national administrative datasets. Competing-risk regression analysis for 3-year cancer-specific mortality was performed according to completion of <6, 6-11, or 12 FOLFOX cycles, or < 4, 4-7, or 8 CAPOX cycles, adjusted for patient, tumour and hospital-level characteristics. Median age was 64 years. 32% of patients had at least one comorbidity. 42% of patients had T4 disease, and 40% N2 disease. Compared to completion of 12 FOLFOX cycles, cancer-specific mortality was higher in patients completing <6 cycles (sHR 2.17; 95% CI, 1.56 to 3.03) or 6-11 cycles (sHR 1.40; 95% CI, 1.09 to 1.78) (P < 0.001). Compared to completion of 8 CAPOX cycles, cancer-specific mortality was higher in patients completing <4 cycles (sHR 2.02; 95% CI 1.53 to 2.67) or 4-7 cycles (sHR 1.63; 95% CI 1.27 to 2.10) (P < 0.001). Dose reduction and early oxaliplatin discontinuation did not impact mortality in patients completing all cycles. Completion of all cycles of chemotherapy was associated with improved cancer-specific survival in real-world practice. Poor prognostic factors may have affected findings, however, patients completing <50% of cycles had poor outcomes. Clinicians may wish to facilitate completion with treatment modification in those able to tolerate it.