Outcomes of Adjuvant Oral versus Intravenous Fluoropyrimidines for High-Risk Stage II or Stage III Colon Adenocarcinoma: A Propensity Score-Matched, Nationwide, Population-Based Cohort Study

Objective: We conducted this propensity score (PS)-matched, nationwide, population-based cohort study to estimate the effects of adjuvant oral or intravenous (IV) fluoropyrimidine in patients with high-risk stage II or III colon adenocarcinoma. Design: Using PS matching, we minimized the confounding effects on adjuvant oral or IV fluoropyrimidine outcomes in patients with high-risk stage II or III resectable colon adenocarcinoma. Setting: We selected patients from the Taiwan Cancer Registry database receiving adjuvant fluoropyrimidine monotherapy and divided them into those receiving IV fluoropyrimidine (IV group) and those receiving oral fluoropyrimidine (oral group). Results: In both univariate and multivariate Cox regression analyses, the adjusted hazard ratio (aHR) derived for the oral group was 1.34 (95% CI: 1.19-1.51) compared with the IV group. Moreover, in both univariate and multivariate analyses, aHR derived for significant independent prognostic risk factors for poor overall survival were male sex, age ≥ 60 years old, pathologic stage III, right-sided colon cancer, low income, and high Charlson comorbidity index. However, intergroup differences were not significant among female patients or patients < 60 years old on multivariate analysis, including no difference in overall survival. Conclusions: Adjuvant IV fluoropyrimidine is more suitable than adjuvant oral fluoropyrimidine for patients with stage II colon adenocarcinoma who have high-risk pathologic features or stage III colon adenocarcinoma.