Efficacy of Splenectomy for Proximal Gastric Cancer with Greater Curvature Invasion or Type 4 Tumor: a Propensity Score Analysis of a Multi-Institutional Dataset.

Splenectomy for proximal gastric cancer was found to have no survival benefit in a randomized trial clarifying the role of splenectomy (JCOG0110 study). However, since tumor with invasion to the greater curvature and Type 4 tumor were excluded in JCOG0110, the benefit of splenectomy for these tumors is not known. A multicenter dataset of patients with gastric cancer who underwent gastrectomy between 2010 and 2014 was created. From the dataset, 114 eligible patients with proximal advanced gastric cancer with invasion to the greater curvature or Type 4 tumor were enrolled. There were 60 patients in the gastrectomy with splenectomy (Spx) group and 54 patients in the spleen-preserving (Prs) group. To balance the essential variables, propensity score analysis was performed, estimating the propensity score with a logistic regression model. Adjusted overall survival (OS) and adjusted disease-free survival (DFS) were estimated using the inverse probability of treatment weighting (IPTW) method. There were significant differences in age, performance status, comorbidity, macroscopic type, and clinical T stage between the Spx and Prs groups. The model for estimating the propensity score was well adapted (c-statistic: 0.830, 95%CI: 0.754–0.906). Adjusted OS was identical between the two groups (HR = 1.089, 95%CI: 0.759–1.563; p = 0.644). The DFS curve of Prs group was consistently tended to be lower than Spx, but the difference was not significant (HR = 0.813, 95%CI: 0.572–1.156; p = 0.249). The efficacy of splenectomy was minimal for proximal advanced gastric cancer even with invasion to the greater curvature or Type 4 tumor.