The prognostic value of sarcopenia combined with preoperative C-reactive protein-albumin ratio in patients with gastric signet ring cell carcinoma

Background Gastric signet ring cell carcinoma (GSRCC) is an aggressive subtype of gastric cancer with poor prognosis. Sarcopenia and systemic inflammation have been linked to adverse outcomes in malignancies. This study aimed to evaluate the prognostic value of sarcopenia combined with systemic inflammatory indices in patients with GSRCC. Methods Patients with GSRCC who underwent curative gastrectomy between 2014 and 2018 were retrospectively analyzed and randomly divided into a training cohort ( n = 392) and an internal validation cohort ( n = 165). Sarcopenia was defined using sex-specific L3 skeletal muscle index (SMI) cutoffs on preoperative CT images. Prognostic factors for overall survival (OS) were identified using univariable Cox, LASSO, and multivariable Cox analyses. Kaplan-Meier analysis was applied to ascertain the prognostic value. A nomogram was constructed and evaluated by concordance index (C-index), calibration curve, and decision curve analysis (DCA). Results Among 557 patients, 264 (47.4%) met the criteria for sarcopenia. Multivariable Cox analysis identified sarcopenia, C-reactive protein-albumin ratio (CAR), TNM stage and tumor location as independent predictors of OS. A novel scoring system, SCAR, integrating sarcopenia and CAR, stratified patients into three risk groups with significantly different survival outcomes. A nomogram incorporating SCAR, tumor location, and TNM achieved good predictive performance with C-index of 0.815 (training) and 0.849 (validation), with favorable calibration and higher net benefit than TNM staging on DCA. Conclusions Elevated preoperative CAR and CT-defined sarcopenia based on low skeletal muscle mass are independently associated with poor survival in patients with GSRCC. The novel prognostic scoring system, SCAR, incorporates host-related factors to complement TNM staging and improves prognostic stratification in GSRCC.