Prognostic impact of the lymph node ratio in rectal cancer patients who underwent preoperative chemoradiation

Aim: The purpose of this study was to investigate the prognostic impact of the lymph node ratio (LNR) in ypN-positive rectal cancer patients who received preoperative chemoradiation (preop-CRT). Methods: A total of 75 patients diagnosed as node-positive after undergoing preop-CRT followed by curative resection were enrolled. Patients were categorized into two groups based on their median LNR, 0.143. Results: The median metastatic and retrieved lymph node numbers were 2.0 (range: 1-79) and 18.0 (range: 5-80). Abdominoperineal resection, circumferential resection margin involvement and higher LNR were proven to be independent adverse prognostic factors affecting survival in the multivariate analysis including LNR as a covariate. Of the 47 patients with ypN1, 35 (74.5%) showed a lower LNR (N1G1) and 12 (25.5%) showed a higher LNR (N1G2). The N1G1 group showed better overall survival than the N1G2 group (P = 0.018). There was no difference between the survival rates of the N1G2 group and the ypN2 group (P = 0.987). Conclusions: LNR is an independent prognostic factor after preop-CRT for rectal cancer. LNR showed better prognosis stratification than the ypN stage. Therefore, LNR should be considered as an additional prognostic factor in node-positive rectal cancer after preop-CRT.