[A long-term follow-up study on recurrence and benefit of standardized postoperative chemotherapy of rectal cancer patients with complete pathological response after neoadjuvant chemoradiotherapy].

Objective: To analyze the clinicopathological factors affecting long-term disease-free survival and the characteristics of local recurrence or distance metastasis of rectal cancer patients with complete pathological response after neoadjuvant chemoradiotherapy. Methods: The clinicopathological data and follow-up information of patients with a complete pathological response of rectal cancer after neoadjuvant chemoradiotherapy in the Cancer Hospital of Chinese Academy of Medical Sciences from June 2004 to December 2019 were retrospectively collected. The clinicopathological factors affecting the long-term disease-free survival of patients were analyzed to build a prediction model of local recurrence and distant metastasis and to evaluate the benefits of postoperative chemotherapy. Results: The age of 108 patients was(56.3±11.6) years, of which 68 were males (63.0%); The median follow-up time was 79.9 (61.8, 112.6) months. There were 12 patients (11.1%) who had a local recurrence or distant metastasis. The 5-year disease-free survival rate was 91.1% with 9 patients who experienced recurrence. Multivariate Cox proportional hazards regression analysis showed that the maximum diameter of the residual tumor or scar (HR=8.41, 95%CI: 1.08-65.22, P=0.042) and the distance from the lower edge of the tumor to the anal margin before treatment (HR=4.54, 95%CI: 1.23-16.81, P=0.023) were independent risk factors affecting the prognosis. The prognosis of patients was stratified based on relevant factors. The 5-year cumulative disease-free survival rate of those patients receiving postoperative standardized chemotherapy was 92.0%, while for patients who did not receive or complete standardized chemotherapy, the 5-year cumulative disease-free survival rate was 82.3%. Conclusions: The maximum diameter of the residual tumor or scar and the distance from the lower edge of the tumor to the anal margin before treatment were independent risk factors affecting the prognosis of patients with a complete pathological response. Patients with independent risk factors could benefit from the standardized postoperative chemotherapy.