Prognostic importance of tumor size in stage II–III diffuse-type gastric cancer: a comparative analysis with intestinal-type gastric cancer

Abstract Purpose Tumor size has been reported as an independent prognostic factor in gastric cancer (GC). However, its impact in diffuse-type gastric cancer (DTGC) remains unclear. The purpose of this study is to evaluate the prognostic value of tumor size in surgically treated stage II–III GC, with comparison to intestinal-type GC (ITGC). Methods We retrospectively analyzed 259 patients with stage II or III GC who underwent curative surgery, including 101 diagnosed with DTGC. Disease specific survival (DSS) was compared between DTGC and ITGC. The prognostic significance of clinicopathologic factors—including sex, age, operative time, intraoperative blood loss, pathological tumor size, T stage, and lymph node metastasis—was assessed using Kaplan–Meier and Cox regression analyses. Results Kaplan–Meier analysis showed no difference in DSS between DTGC and ITGC ( P = 0.9). In univariate Cox regression, T stage was significantly associated with DSS only in ITGC ( P = 0.001), while lymph node status was significantly associated with DSS in both ITGC and DTGC ( P = 0.008, P = 0.005, respectively). Notably, tumor size was significantly associated with DSS only in DTGC ( P = 0.001). In multivariate analysis, tumor size and lymph node status were independent prognostic factors in DTGC ( P = 0.008, P = 0.01, respectively), whereas T stage and lymph node status were independent prognostic factors in ITGC ( P = 0.001, P = 0.003, respectively). Conclusions In stage II–III DTGC, tumor size is a more relevant prognostic factor than T stage. These findings suggest that tumor size should be considered in postoperative risk stratification, and that patients with large DTGC tumors warrant particularly careful surveillance.