Retrospective Evaluation of CTI as a Prognostic Marker in Locally Advanced Gastric and Gastroesophageal Junction Adenocarcinoma Treated with Perioperative FLOT

Background The C-reactive protein-Triglyceride-Glucose Index (CTI), integrating C-reactive protein and the triglyceride–glucose index, has recently emerged as a pragmatic biomarker reflecting systemic inflammation and metabolic stress in cancer. Although its prognostic value has been validated in heterogeneous cancer cohorts, data in homogeneous perioperative settings remain limited. Methods We retrospectively evaluated 131 patients with locally advanced gastric or gastroesophageal junction adenocarcinoma who received perioperative FLOT chemotherapy between 2018 and 2024. CTI was calculated at diagnosis, and patients were stratified using the 4.78 cut-off value previously validated in oncology populations. Associations between CTI and clinicopathological variables, pathological response, progression-free survival (PFS), and overall survival (OS) were analyzed. Results Among 131 patients who underwent curative-intent surgery after neoadjuvant FLOT, 113 (86.3%) had low CTI (< 4.78) and 18 (13.7%) had high CTI (≥ 4.78). Patients with high CTI had significantly shorter progression-free survival (PFS) compared with those with low CTI (median 6.6 vs. 31.4 months, p = 0.006). Overall survival (OS) was also markedly inferior in the high CTI group (median 23.1 months vs. not reached in the low CTI group, p = 0.001). In multivariable analysis, high CTI independently predicted poor PFS (HR = 2.18, 95% CI 1.21–3.95, p = 0.010). Regarding treatment response, the pathological complete response (pCR) rate was 11.5% (13/113) in the low CTI group and 22.2% (4/18) in the high CTI group (p = 0.221), indicating no significant association between CTI and pathological response. Conclusions Pretreatment CTI is an independent prognostic marker in patients with locally advanced gastric or gastroesophageal junction adenocarcinoma treated with perioperative FLOT, identifying individuals at higher risk of relapse and inferior survival. Its simplicity, low cost, and pretherapeutic availability support CTI as a promising tool for risk stratification that warrants prospective multicentre validation.