Lack of oncological significance of prophylactic splenectomy for type 4 gastric cancer invading the greater curvature: a multicenter retrospective study.

The necessity of prophylactic splenectomy for 4 gastric cancer with greater curvature invasion remains unclear, as this subtype was excluded from the pivotal JCOG0110 trial. This study aimed to evaluate the short-term and long-term outcomes of splenectomy specifically in this population. We analyzed patients with clinically diagnosed advanced (cT2 or deeper) type 4 gastric cancer invading the greater curvature who underwent radical total gastrectomy at 11 institutes between 2005 and 2015. To minimize selection bias, inverse probability of treatment weighting (IPTW) was performed. Patients with clinical No. 10 lymph node metastasis or direct splenic invasion were excluded. A total of 95 patients were included (Splenectomy: n = 48; NonSplenectomy: n = 47) after IPTW adjustment. The Splenectomy group had a significantly higher incidence of intra-abdominal infectious complications compared to the NonSplenectomy group (20.8% vs. 4.3%; p = 0.04). Pathological metastasis to the No. 10 nodes was confirmed in 22.9% of the Splenectomy group. However, no significant differences were observed between the two groups in either 5-year relapse-free survival (HR 0.99; p = 0.66) or 5-year overall survival (HR 1.22; p = 0.91). Peritoneal dissemination was the predominant pattern of recurrence in both groups (> 94%). For type 4 gastric cancer invading the greater curvature, prophylactic splenectomy increases the risk of postoperative infectious complications without providing a survival advantage.