Effects of Adjuvant Chemotherapy on Oncologic Outcomes in Patients With Stage ⅡA Rectal Cancer Above the Peritoneal Reflection Who Did Not Undergo Preoperative Chemoradiotherapy

This study aimed to evaluate the effects of adjuvant chemotherapy (AC) on oncologic outcomes for patients with stage IIA upper rectal cancer and to investigate whether AC is associated with improved survival outcomes. This retrospective study comprised 432 patients with rectal cancer above the peritoneal reflection who had undergone curative resection without preoperative chemoradiotherapy between 2008 and 2016. This study cohort was divided according to whether AC was received (AC group) or not (no-AC group). Risk factors included obstruction, perforation, poorly-differentiated tumor, lympho-vascular invasion, perineural invasion, resection margin involvement, and < 12 lymph nodes harvested. Among the 432 patients, 279 (64.6%) had received AC. The AC group had significantly higher 5-year overall survival (OS) rates than those of the no-AC group (93.2% vs 84.6%, = .001). Among patients with ≥ 1 risk factors, the AC group (n = 123) had significantly higher rates of 5-year recurrence-free survival (RFS) (81.6% vs 64.1%, = .01) and 5-year OS (88.8% vs 69.0%, = .001) than those of the no-AC group (n = 59). No significant difference in survival outcomes was observed between the 2 groups in patients aged > 65 years. AC was significantly associated with better 5-year RFS and 5-year OS rates in patients with stage IIA rectal cancer above peritoneal reflection who did not receive preoperative chemoradiotherapy, especially in those with ≥ 1 risk factors.