Can yStage Ⅰ/Ⅱ rectal cancer patients be treated in the same way as stage Ⅰ/Ⅱ patients?

Background: Neoadjuvant therapy (NAT) before radical surgery are effective treatments for locally advanced rectal cancer. However, the treatment strategy after NAT and surgery is still unclear. It is difficult to accurately evaluate the stage before NAT, as some cases are downstaged by NAT. Objective: We investigated the treatment strategies based on the postoperative pathology of patients with yStage Ⅰ or Ⅱ rectal cancer who underwent NAT and radical resection. Design: They patients were retrospectively evaluated the long-term outcomes. They were divided into patients with yStage I/II receiving NAT and patients with stage I/II patients without NAT (non-NAT). Disease-free survival (DFS) and overall survival (OS) were examined, and the prognosis was compared. Cox proportional hazard model was used to examine the recurrence risk factors in all patients or NAT. We compared the effects of adjuvant therapy in NAT. Patients: Overall, 521 patients histologically diagnosed with yStage I/II or stage I/II who underwent surgery for rectal cancer between April 2001 and July 2019 were eligible. Results: The NAT and non-NAT groups included 80 and 441 patients, respectively. DFS was significantly lower in NAT, but there was no difference in OS between the two groups. All patients had several recurrence risk factors, but none of the NAT had such risk factors. No significant difference in DFS and OS was found between NAT with and without adjuvant chemotherapy. Limitation: This is a single-center retrospective study. Conclusions: NAT had lower DFS than non-NAT, but no difference in OS was observed. No significant recurrence risk factors were observed in NAT. Adjuvant chemotherapy for NAT may have no benefit.