Is There a Role for Adjuvant Chemotherapy in Pathologic Node-Negative Locally Advanced Rectal Cancer After Neoadjuvant Chemoradiation Therapy?

Background: Neoadjuvant chemoradiation therapy (NCRT, 5-fluorouracil and radiation) followed by resection and adjuvant chemotherapy (AC) is one of the standard treatment paradigms for locally advanced rectal adenocarcinoma. However, the utility of AC in patients with pathologic lymph node (pLN)-negative disease is unclear. Our aim is to assess the value of AC stratified by pLN status. Methods: The US Rectal Cancer Consortium database (2007–2017) was retrospectively reviewed for patients with clinical stage II and III rectal adenocarcinoma who received neoadjuvant chemoradiation (NACR) and curative-intent resection. Those who received neoadjuvant systemic chemotherapy or underwent local resection were excluded. Patients were categorized by pLN status. Primary outcome was overall survival (OS). Results: Of 213 patients, 70% had pLN-negative disease and 30% pLN-positive disease. Median age was 57 years, 65% were male, and median follow-up was 31 months. Among patients with pLN-negative disease, 74% received AC. Receipt of AC was not associated with improved 5-year OS (82% versus 74%, respectively; p = 0.16). This finding persisted on multivariable analysis. Of patients with pLN-positive disease, 83% received AC. Patients with pLN-positive disease demonstrated improved 5-year OS with receipt of AC (72% compared with 0% with no adjuvant chemotherapy, p = 0.04). Conclusion: After receiving neoadjuvant chemoradiation, adjuvant chemotherapy for patients with pLN-negative disease does not appear to be associated with improved survival. Further validation and prospective studies are needed to evaluate the utility of adjuvant chemotherapy in this setting.