Development and prognostic evaluation of a combined SII–LNR score in resectable gastric and gastroesophageal junction adenocarcinoma treated with perioperative FLOT: a retrospective single-center study

Background The systemic immune-inflammation index (SII) and lymph node ratio (LNR) have both been associated with survival in gastric and gastroesophageal junction (GEJ) adenocarcinoma, but their combined prognostic value is unclear in patients treated with perioperative fluorouracil, leucovorin, oxaliplatin, and docetaxel (FLOT). We developed a combined SII–LNR risk score and assessed its association with overall survival (OS) and disease-free survival (DFS). Methods This retrospective single-center cohort included 153 patients with resectable gastric or GEJ adenocarcinoma treated with perioperative FLOT. SII was calculated from pretreatment complete blood counts and LNR from postoperative pathology. OS and DFS were evaluated using Kaplan–Meier methods and Cox proportional hazards regression. Cut-offs were defined using receiver operating characteristic (ROC) analysis with the Youden index, and area under the curve (AUC) values were reported. Results ROC-derived cut-offs were 715 for SII (AUC 0.602) and 0.13 for LNR (AUC 0.751). The combined SII–LNR score categorized patients into low-risk ( n = 50, 32.7%), moderate-risk ( n = 67, 43.8%), and high-risk ( n = 36, 23.5%) groups. Median OS was 41.5, 30.5, and 17.2 months, with 5-year OS rates of 40.5%, 17.1%, and 4.4%. Median DFS was 32.4, 15.6, and 10.8 months, with 5-year DFS rates of 34.2%, 17.4%, and 5.7%. Compared with the low-risk group, the risk of death was higher in the moderate- and high-risk groups (HR 1.93, 95% CI [1.15–3.26]; HR 4.13, 95% CI [2.37–7.22]) and the risk of recurrence or death was also higher (HR 2.07, 95% CI [1.25–3.42]; HR 3.58, 95% CI [2.12–6.02]). Conclusion The combined SII–LNR score stratified patients with resectable gastric and GEJ adenocarcinoma treated with perioperative FLOT into distinct postoperative OS and DFS risk groups. If confirmed in multicenter cohorts, it may help identify patients who warrant closer postoperative follow-up.