Effect of Responsiveness of Lymph Nodes to Preoperative Chemoradiotherapy in Patients With Rectal Cancer on Prognosis After Radical Resection

Metastatic lymph node status after preoperative chemoradiotherapy can be evaluated using the lymph node regression grade (LRG). In this study, the LRG was shown to discriminate prognostic groups, even within the same ypN stage, indicating that LRG can be considered a prognostic determinant in rectal cancer patients with metastatic lymph nodes after preoperative chemoradiotherapy. Background: The influence of lymph node (LN) response to preoperative chemoradiotherapy (PCRT) has not been well evaluated for prognosis and additional use of adjuvant treatment after PCRT in rectal cancer patients. The aim of this study was to evaluate the prognostic effect of LN regression grade (LRG) in rectal cancer after PCRT and radical resection. Patients and Methods: From 2008 to 2011, 389 patients with rectal cancer treated with PCRT followed by radical resection were identified. The pathologic LRG (pLRG) score was determined on the basis of the proportion of tumor cells and fibrosis. The sum of the pLRG of each evaluated LN was used as the final LRG score, LRG-sum. Cox regression analysis was used to evaluate the association of LRG-sum and recurrence-free survival (RFS). Results: The distribution of LRG-sum was significantly associated with tumor regression grade of the primary tumor (P < .001). LRG-sum showed different values even in patients with the same number of metastatic LNs. LRG-sum was confirmed as the most relevant associated factor among LN-related variables with RFS along with ypT stage in multivariate analysis. Patients were categorized according to the cutoff points of LRG-sum distribution: LRG1 (LRG-sum 0 to <3), LRG2 (LRG-sum 3 to <= 21), and LRG3 (LRG-sum >21). RFS showed a significant difference according to LRG group (P < .001) and showed more effective difference in RFS in the same ypN stage subgroup on the basis of the number of metastatic LNs. Conclusion: LRG was a prognostic factor of oncologic outcomes of rectal cancer. LN response to PCRT might help in prognostication and determination of treatments after PCRT. (C) 2019 The Authors. Published by Elsevier Inc.