Evaluating the benefit of adjuvant chemotherapy in patients with ypT0-1 rectal cancer treated with preoperative chemoradiotherapy.

Background: Adjuvant chemotherapy (ACTx) is recommended in rectal cancer patients after preoperative chemoradiotherapy (PCRT), but its efficacy in patients in the early post-surgical stage who have a favorable prognosis is controversial.

Aim: To evaluate the long-term survival benefit of ACTx in patients with ypT0-1 rectal cancer after PCRT and surgical resection.

Methods: We identified rectal cancer patients who underwent PCRT followed by surgical resection at the Asan Medical Center from 2005 to 2014. Patients with ypT0-1 disease and those who received ACTx were included. The 5-year overall survival (OS) and 5-year recurrence-free survival (RFS) were analyzed according to the status of the ACTx.

Results: Of 520 included patients, 413 received ACTx (ACTx group) and 107 did not (no ACTx group). No significant difference was observed in 5-year RFS (ACTx group, 87.9% no ACTx group, 91.4%, = 0.457) and 5-year OS (ACTx group, 90.5% no ACTx group, 86.2%, = 0.304) between the groups. cT stage was associated with RFS and OS in multivariate analysis [hazard ratio (HR): 2.57, 95% confidence interval (CI): 1.07-6.16, = 0.04 and HR: 2.27, 95%CI: 1.09-4.74, = 0.03, respectively]. Furthermore, ypN stage was associated with RFS and OS (HR: 4.74, 95%CI: 2.39-9.42, < 0.00 and HR: 4.33, 95%CI: 2.20-8.53, < 0.00, respectively), but only in the radical resection group.

Conclusion: Oncological outcomes of patients with ypT0-1 rectal cancer who received ACTx after PCRT showed no improvement, regardless of the radicality of resection. Further trials are needed to evaluate the efficacy of ACTx in these group of patients.