Refining the Use of Adjuvant Oxaliplatin in Clinical Stage II or III Rectal Adenocarcinoma

Background: Current guidelines include the use of adjuvant oxaliplatin in clinical stage II or III rectal adenocarcinoma. However, its efficacy is supported by a single phase II trial. We aimed to examine whether oxaliplatin confers survival benefit in this patient population. Methods: Using the National Cancer Database (2006–2013) we identified 6,868 individuals with clinical stage II or III rectal adenocarcinoma treated with neoadjuvant chemoradiotherapy, surgery, and adjuvant chemotherapy. We used multivariate Cox regression to evaluate survival differences according to treatment intensity and change from clinical to pathological stage. Results: We demonstrated an association with improved overall survival with the use of doublet adjuvant chemotherapy in pathological stage III rectal adenocarcinoma (hazard ratio [HR], 0.78; 95% confidence interval [CI], 0.67–0.92). This association was confirmed in patients with clinical stage III and subsequent pathological stage III disease (HR, 0.69; 95% CI, 0.57–0.83) and was not observed in patients who progressed from clinical stage II to pathological stage III disease. Doublet adjuvant chemotherapy was not associated with improved overall survival in patients with pathological stage 0 or I disease, regardless of their clinical stage. Conclusion: Adjuvant oxaliplatin following neoadjuvant chemoradiotherapy in rectal adenocarcinoma was confirmed in patients with clinical stage III and subsequent pathological stage III disease. Omission of oxaliplatin can be considered in pathological complete response or pathological stage I disease. Implications for Practice: Current guidelines include the use of oxaliplatin as part of adjuvant chemotherapy (AC) in patients with clinical stage II or III rectal adenocarcinoma (RAC). However, its efficacy is supported only by a single phase II trial. This study found an association with improved overall survival with the use of doublet AC in patients diagnosed with clinical stage III and subsequent pathological stage III, and not in patients with pathological stage 0 or I, regardless of their clinical stage. Therefore, omission of oxaliplatin can be considered in patients with either pathological complete response or pathological stage I RAC, thereby avoiding oxaliplatin-induced neuropathy.