Incidence and associated factors of venous thromboembolism in patients with gastric cancer across treatment settings after diagnosis: a systematic review and meta-analysis

Venous thromboembolism (VTE) is a major complication in patients with cancer. Although gastric cancer is recognized as a high-risk malignancy for VTE, existing evidence has mainly focused on perioperative settings. The burden of thrombotic events across broader treatment settings after diagnosis remains less well characterized. This study aimed to estimate the incidence of thrombotic events in patients with gastric cancer across treatment settings after diagnosis and to summarize reported associated factors. A systematic review and meta-analysis was conducted in accordance with PRISMA 2020 guidelines. PubMed, Embase, Web of Science, and the Cochrane Library were searched from inception to January 31, 2026. Studies reporting thrombotic event incidence and/or associated factors in patients with pathologically confirmed gastric cancer were included. Random-effects models were applied. Heterogeneity was assessed using the I² statistic. Sensitivity and exploratory subgroup analyses were performed where applicable. Ten studies comprising 9,689 patients were included. In the primary analysis, the pooled incidence of thrombotic events across treatment settings after diagnosis was 9.0% (95% CI 6.1%–13.2%), with substantial heterogeneity (I² = 97.4%). Quantitative analyses of associated factors, including sex, body mass index ≥ 25 kg/m², peritoneal metastasis, lung metastasis, and bone metastasis, did not establish consistent and reproducible independent associations under random-effects models. Thrombotic risk appears clinically relevant in patients with gastric cancer across treatment settings after diagnosis, beyond short-term perioperative settings. However, current evidence does not establish robust and reproducible predictors for direct clinical implementation. Further large-scale prospective studies are needed to improve risk estimation and support future validation of risk assessment approaches in this population.