No Benefit from More than 3 Months of Adjuvant Oxaliplatin in Colon Cancer

Based on the recent large international IDEA collaboration, 3 months of capecitabine/oxaliplatin or FOLFOX is now considered standard adjuvant therapy for patients with low-risk (T3N1) stage III colon cancer. For patients with high-risk (T4 or N2) stage III disease, 6 months of FOLFOX can be considered; 3 months of capecitabine/oxaliplatin is acceptable for both low-risk and high-risk stage III disease (NEJM JW Oncol Hematol May 2018 and N Engl J Med 2018; 378:1177).

Now, in a pooled analysis of the IDEA and ACCENT databases, investigators evaluated the impact on survival of early discontinuation of all treatment (ETD; receiving <75% of planned chemotherapy cycles) and early discontinuation of oxaliplatin (EOD; receiving <75% of planned oxaliplatin cycles) while continuing fluorinated pyrimidine. Trials in the IDEA database included 3-month and 6-month duration of therapy; those in ACCENT, 6-month duration.

In multivariable analyses adjusted for prognostic factors, ETD was associated with a significant decrease in 3-year disease-free survival (DFS) compared with no ETD (69.0% vs.78.8%; hazard ratio, 1.16; P <0.001) and a decrease in 5-year overall survival (OS; 74.7% vs. 84.7%; HR, 1.73; P <0.001). However, in the subgroup of patients with low-risk stage III disease treated with capecitabine/oxaliplatin, 3-year DFS was similar in the ETD and no-ETD groups (79.0% and 84.0%; HR, 1.21; P=0.1). In contrast, EOD was not associated with reduced DFS or OS in all patients (5-year OS, 89% and 90%; HR, 1.25; P =0.04). However, patients who received <50% of planned oxaliplatin cycles had shorter DFS (HR, 1.34) and OS (HR, 1.61) than those who received all planned cycles.