Clinicopathological Features and Prognostic Impact of Microscopic Resection Margin Positivity After Curative Gastrectomy for Gastric Cancer.

[BACKGROUND/AIM] The incidence of positive microscopic margins after gastrectomy for gastric cancer (GC) has been reported between 1% to 5%. The aim of the present study was to identify risk factors associated with positive microscopic resection margin in GC patients undergoing gastrectomy, and to assess the survival outcomes and prognostic factors in these patients.

[PATIENTS AND METHODS] The patients were selected from the consecutive database of Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Department of Gastric Surgery, according to the following criteria: (i) histologically proven gastric adenocarcinoma (ii) patients who underwent curative gastrectomy for gastric cancer as a primary treatment and archived R0 or R1 resection between 2005 and 2025. Positive microscopic resection margin was defined as disease present at the line of luminal transaction in mucosa, submucosa, or serosa on final pathology. Univariate and multivariate logistic regression analyses were performed to identify risk factors for resection margin positivity.

[RESULTS] A total of 1,996 patients were eligible for the present study. Among these patients, 35 patients (1.8%) had positive microscopic resection margin. Pathological type, macroscopic tumor type, and tumor size were identified as independent risk factors for positive resection margin in multivariate analysis. Moreover, positive peritoneal lavage cytology was identified as an independent predictor of poor overall survival prognostic factor in margin-positive GC patients.

[CONCLUSION] Microscopic resection margin positivity after gastrectomy for GC was linked to specific tumor characteristics, while positive peritoneal lavage cytology independently predicted poorer survival. To minimize the occurrence of resection margin-positive GC after gastrectomy, it is essential to identify risk factors during perioperative evaluation. Furthermore, treatment strategies based on lavage cytology status could improve prognosis in high-risk patients.