Distinct metastatic patterns and survival outcomes in intestinal- versus diffuse-type gastric cancer: a SEER-based propensity score-matched analysis.

BACKGROUND: To investigate the prognostic significance of Lauren classification in metastatic gastric cancer (GC), its association with metastatic patterns, and the prognostic impact of metastatic sites. METHODS: A retrospective cohort study was conducted using the Surveillance, Epidemiology, and End Results (SEER) database. Propensity score matching (PSM) was applied to reduce baseline imbalances. Survival outcomes, including overall survival (OS) and gastric cancer-specific survival (GCSS), were analyzed using Kaplan-Meier methods and multivariate Cox regression. RESULTS: A total of 4,696 patients with metastatic GC were included, comprising 3,758 intestinal-type and 938 diffuse-type cases. After PSM, 934 matched pairs were analyzed. Intestinal-type GC was associated with a higher incidence of liver metastasis and a lower incidence of bone metastasis compared with diffuse-type GC. Multivariate Cox regression analysis indicated that diffuse-type GC was an independent adverse prognostic factor for OS and GCSS both before and after PSM adjustment. Kaplan-Meier analyses demonstrated differences in survival outcomes according to metastatic site, with patients presenting with liver metastasis showing relatively longer survival than those with bone, brain, or multiple-site metastases. CONCLUSIONS: Lauren classification is significantly associated with distinct metastatic patterns and survival outcomes in metastatic GC. These findings may help refine prognostic stratification and support more individualized risk assessment based on histological subtype and metastatic distribution.