Survival impact of CAPOX versus FOLFOX in the adjuvant treatment of stage III colon cancer.

Abstract

710 Background: CAPOX and FOLFOX are used interchangeably in the adjuvant treatment of colon cancer despite the lack of comparative phase III trials.We aimed to compare toxicities, relative dose intensity (RDI), disease free (DFS) and overall survival (OS) of these regimens in the real world. Methods: We identified consecutively treated patients (pts) with stage III colon cancer at two centers who received either CAPOX or mFOLFOX6 when either option was accessible to pts. RDI was defined as total dose received divided by the total intended dose if all cycles had been delivered. Dose limiting toxicities (DLTs) were toxicities that resulted in a dose reduction of an agent. Survival was compared with the log-rank test and Cox models that adjusted for age, gender, ECOG, T-stage, and N-stage. Results: Of 394 pts, 61.7% received FOLFOX. Age, gender, ECOG, T-stage, N-stage, and time between surgery and start of therapy did not differ between groups. However, RDI and toxicity profiles differed between treatment groups (see Table). With a median follow up of 45 months, there was no difference in OS (HR 0.73, 95%CI 0.45-1.22; P= 0.24); however, CAPOX was associated with a more favorable DFS (HR 0.61, 95% CI 0.40-0.93; P= 0.022). In multivariate analysis, treatment with CAPOX showed trends towards improved OS (HR 0.61, 95% CI 0.34-1.07; P= 0.086). A significant association with improved DFS (HR 0.53, 95% CI 0.33-0.87; P= 0.012) persisted. Exploratory analysis comparing outcomes stratified by the presence of any DLT, neutropenia, thrombocytopenia, and neuropathy failed to show an association with either OS or DFS. (See table.) Conclusions: Our findings suggest that the use of adjuvant CAPOX is associated with an improved DFS despite greater toxicity and lower RDI. Patient selection, the higher starting dose of oxaliplatin in CAPOX, or the metronomic nature of capecitabine may be contributing to improved efficacy of CAPOX. [Table: see text]