To investigate the clinical related factors of pathologic complete response (pCR) after neoadjuvant radiotherapy and chemotherapy for locally advanced rectal cancer.

The clinical data of 117 patients with locally advanced rectal cancer treated in intestinal surgery ward of Sichuan Cancer Hospital from January 2013 to May 2018 were retrospectively analyzed. The clinical related factors of pathologic complete response were studied by univariate analysis and logistic binary classification multivariate regression analysis.

A total of 117 patients were enrolled in the study. All of them completed neoadjuvant radiotherapy, chemotherapy and radical surgery. Nineteen patients (16.24%) achieved pathologic complete response. Univariate analysis showed that the sex was female (P=0.024), the age was younger (P=0.042), the level of CEA before radiotherapy was less than 5 ug/L (P=0.015), no smoking history (P=0.008), no drinking history (P=0.037), the distance between tumor and anal margin was greater than 6 cm (P=0.048) and the high pathologic complete response after neoadjuvant radiotherapy and chemotherapy for locally advanced rectal cancer. The rate is related. Multivariate regression analysis showed that the CEA level before radiotherapy was less than 5 ug/L (P=0.039) and the distance between the tumor and the anal margin was more than 6 cm (P=0.043) were independent factors affecting the pathologic complete response rate of locally advanced rectal cancer after neoadjuvant radiotherapy and chemotherapy.

The level of CEA before radiotherapy and the distance between the tumor and the anal margin may be related to the rate of pathologic complete response after neoadjuvant radiotherapy and chemotherapy for locally advanced rectal cancer.