Prognostic Impact of Metastasis Timing in Metastatic Gastrointestinal Stromal Tumors: A Multicenter Retrospective Cohort Study

Background Gastrointestinal stromal tumors (GISTs) commonly metastasize to the liver and peritoneum. Metastases may be detected synchronously at the time of initial diagnosis or develop metachronously after curative‐intent resection. Nonetheless, the prognostic significance of metastasis timing in advanced GIST remains unclear. Methods We retrospectively analyzed 147 patients with metastatic GIST treated at multiple institutions between 2003 and 2012. The patients were categorized into synchronous ( n = 51) and metachronous ( n = 96) groups. Clinicopathological characteristics and overall survival (OS) were compared using Kaplan–Meier analysis and Cox proportional hazards models. Among patients with metachronous disease, the outcomes were further evaluated according to the recurrence interval. Results The median OS was significantly shorter in the synchronous group (6.7 years) than in the metachronous group (12.8 years; p = 0.001). Metastasis timing remained an independent prognostic factor in multivariable analysis (hazard ratio 2.36, 95% confidence interval 1.39–4.00; p = 0.001). Among patients with metachronous metastasis, early recurrence within 2 years after surgery was associated with significantly inferior survival compared to late recurrence. Conclusion Metastasis timing was associated with survival in patients with metastatic GIST. Both synchronous presentation and early metachronous recurrence were associated with poorer outcomes.