Prognostic Value of the Extramural Perivenous Infiltration in Locally Advanced Gastric Cancer: A Retrospective Clinical Study.

BACKGROUND: Gastric cancer (GC) remains a leading cause of cancer-related mortality worldwide. This study aims to investigate the prognostic value of extramural perivenous infiltration (EMPVI) and to establish a dynamic prediction model for locally advanced GC. METHODS: We retrospectively analyzed 223 consecutive patients with locally advanced GC who underwent D2 gastrectomy followed by adjuvant chemotherapy between September 2014 and April 2019. D2-40 and elastic fiber staining were performed to distinguish EMPVI and extramural venous invasion (EMVI), with results compared to hematoxylin and eosin (H&E) staining using weighted kappa (κ) statistics. The Kaplan-Meier method with log-rank test was used to estimate the 5-year disease-free survival (DFS). The chi-square (χ2) test was applied to analyze the associations between clinicopathological characteristics and EMPVI or 5-year DFS. Variables significant in univariate analysis were entered into a multivariate Cox regression model. All tests were two-sided, and P < 0.05 was considered statistically significant. RESULTS: EMPVI was more common than EMVI (54.7% vs. 18.4%). EMPVI positivity correlated with worse 5-year DFS (P = 0.000) and was significantly associated with tumor stage (T), lymph node metastasis, perineural invasion, and tumor deposits (P < 0.01). Univariate analysis identified EMPVI, tumor stage (T), lymph node metastasis, perineural invasion, tumor deposits, Lauren classification, and tumor differentiation as risk factors for 5-year DFS (P < 0.05). Multivariate Cox regression analysis confirmed EMPVI (P = 0.000), Lauren classification (P = 0.001), and tumor stage (T) (P = 0.018) as independent prognostic indicators for 5-year DFS. CONCLUSIONS: EMPVI serves as a novel and robust independent prognostic indicator in locally advanced GC.