Prognostic significance of lymph node-related indices and a novel nomogram for rectal cancer patients with synchronous liver metastases after the preoperative chemoradiotherapy: a population-based study

Background: Patient outcomes in rectal cancer with synchronous liver metastases remain heterogeneous, underscoring the need for reliable prognostic factors to guide individualized treatment strategies. This study sought to assess the influence of lymph node-related indices on the survival of rectal cancer patients with synchronous liver metastases who underwent preoperative chemoradiotherapy and to construct a novel nomogram for this patient population. Methods: Data on rectal cancer patients with synchronous liver metastases who underwent preoperative chemoradiotherapy between 2010 and 2019 were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. X-tile software was employed to determine the optimal cutoff point of lymph node-related indices. The Kaplan-Meier method and log-rank test were used to assess survival differences. Cox univariate and multivariate analyses were conducted to identify the prognostic factors for overall survival (OS). We constructed a novel nomogram to predict individual survival probability. The concordance index (C-index) and calibration curve were used to determine the predictive accuracy and discriminative ability of the nomogram. Results: . 12.6%, P