The impact of the radiation-induced regression of positive nodes on survival in patients with rectal cancer treated with chemoradiotherapy.

BACKGROUND: Although preoperative chemoradiotherapy exerts a destructive effect on positive lymph nodes, microscopic examination reveals different degrees of tumor regression. The aim of the present study is to investigate the impact of the radiation-induced regression of positive nodes on survival in patients with rectal cancer treated with preoperative chemoradiotherapy.

METHODS: From 2001 to 2015, 229 patients with T3 rectal cancer underwent total mesorectal excision after preoperative chemoradiotherapy. The patients were classified into 3 groups according to their lymph node status: residual cancer cells in positive nodes (Group A), total regression of positive nodes after preoperative chemoradiotherapy with complete fibrosis (Group B), and the entire lymph node filled with lymph nodules and the absence of fibrosis (Group C). The survival of the 3 groups was compared, and a Cox model was used to evaluate the prognostic value of the regression of the positive nodes by preoperative chemoradiotherapy.

RESULTS: Groups A, B, and C included 57, 18, and 154 patients, respectively. Group B showed significantly better overall survival than Group A (P = .041) and similar outcomes to Group C (P = .383). Among the patients with positive lymph nodes prior to treatment (Groups A and B), the total regression of the positive nodes after preoperative chemoradiotherapy was the only independent factor to be associated with good overall survival (hazard ratio; 6.26, 95% confidence interval; 1.28-113.0, P = .020).

CONCLUSION: Total regression of positive nodes by preoperative chemoradiotherapy improves the prognosis of patients with rectal cancer with positive lymph nodes prior to treatment.