Prognostic Value of Tumor Regression Grade Combined with Pathological Lymph Node Status in Initially Node-Positive Rectal Cancer Treated with Neoadjuvant Chemoradiotherapy.

Background: The prognostic value of tumor regression grade (TRG) after neoadjuvant chemoradiotherapy for rectal cancer is inconsistent in the literature. Both TRG and post-therapy lymph node (ypN) status could reflect the efficacy of neoadjuvant therapy. Here, we explored whether TRG combined with ypN status could be a prognostic factor for MRI-based lymph node-positive (cN+) rectal cancer following neoadjuvant chemoradiotherapy.

Methods: 671 cN + rectal cancer patients who received neoadjuvant chemoradiotherapy followed by radical resection were enrolled. Patients were innovatively divided into three groups based on TRG and ypN status: TRG0-1N0, TRG2-3N0 or TRG0-1N+, TRG2-3N+. Kaplan-Meier method and log-rank test were used to compare the disease-free survival (DFS) and overall survival (OS) among three groups. Univariate and multivariate analyses were performed to explore the prognostic value of the modified TRG in cN + rectal cancer following neoadjuvant chemoradiotherapy.

Results: The mean duration of follow-up was 30.4 months. Significant survival differences were observed among the three groups. The 3-year DFS were 83.0%, 69.2% and 55.9%, respectively. The 5-year OS were 83.5%, 80.4% and 57.8%, respectively. TRG combined with ypN status was an independent predictor for both DFS and OS in multivariate analysis.

Conclusion: TRG combined with ypN status is a novel prognostic factor in cN + rectal cancer following neoadjuvant chemoradiotherapy, which assists clinicians make appropriate decisions regarding postoperative treatment and surveillance.