Risk-Adapted Adjuvant Chemotherapy After Concomitant Fluoropyrimidine–Radiotherapy Neoadjuvant Treatment for Patients With Resectable CT3-4 or N+ Rectal Cancer: Five-Year Disease-Free Survival Results of a Single-Center Series

Abstract Background Providing adjuvant chemotherapy in locally advanced rectal cancer after neoadjuvant chemoradiation is currently a matter of debate. Recommendations from clinical guidelines range from offering no treatment to oxaliplatin-based combinations. We present a risk-adapted approach based on the response to initial chemoradiation as the strongest prognostic factor for disease-free survival (DFS). Patients and Methods One hundred one patients were treated at a single institution with preoperative long-course radiotherapy plus concurrent fluoropyrimidines. Patients with disease downstaged to pT0-2N0 received adjuvant fluoropyrimidines alone, while the remaining received an oxaliplatin-based combination. The primary study end point was 5-year DFS. Results Overall, the disease of 54 patients was downstaged to pT0-2N0 (53.5%), while that of 47 patients was staged as pT3-4 or N+ (46.5%) after surgery. In the intention-to-treat analysis, 5-year DFS for patients in the good-prognosis group (downstaging to pT0-2 N0) and for those with poor prognosis (pT3-4 or N+) were 79.4% and 66.3%, respectively (hazard ratio, 0.489; P  = .043). Downstaging and pN+ were independent prognostic factors for DFS. Conclusion A risk-adapted adjuvant therapy strategy based on pathologic stage after neoadjuvant chemoradiation is feasible and achieves high rates of 5-year DFS. Patients with good prognostic factors can be treated with adjuvant fluoropyrimidines alone, thus permitting the avoidance of oxaliplatin-derived toxicities.