Efficacy of chemotherapy versus surgery as initial treatment for gastric cancer with positive peritoneal cytology.

BACKGROUND: The prognosis of gastric cancer (GC) patients with positive peritoneal cytology (CY1) without other distant metastasis is poor, and there are no standard treatment strategies. Our study aimed to compare the survival outcomes of CY1 GC patients receiving chemotherapy or surgery as initial treatment. METHODS: From February 2017 to January 2020, clinical and pathological data of patients diagnosed with CY1 GC without other distant metastasis in the Peking University Cancer Hospital was reviewed. Patients were divided into two groups: chemotherapy-initial group and surgery-initial group. In chemotherapy-initial group, patients received preoperative chemotherapy initially. According to the treatment response, the patients were divided into three subgroups: conversion gastrectomy group, palliative gastrectomy group, and further systematic chemotherapy group. In surgery-initial group, patients underwent gastrectomy followed by postoperative chemotherapy. RESULTS: A total of 96 CY1 GC patients were included with 48 patients in each group. In chemotherapy-initial group, preoperative chemotherapy yielded an objective response rate of 20.8% and disease control rate of 87.5%. Conversion to CY0 after preoperative chemotherapy was obtained in 24 (50%) patients. The median overall survival was 36.1 months in chemotherapy-initial group and 29.7 months in surgery-initial group (p = 0.367). The median progression-free survival was 18.1 months in chemotherapy-initial group and 16.1 months in surgery-initial group (p = 0.861). The 3-year overall survival rates were 50.0% and 47.9%, respectively. In chemotherapy-initial group, twenty-four patients who converted to CY0 by preoperative chemotherapy and received surgery obtained a significantly better prognosis. The median overall survival was still not reached in these patients. CONCLUSION: There was no significant difference in survival outcomes between chemotherapy-initial group and surgery-initial group. CY1 GC patients who converted to CY0 by preoperative chemotherapy and received radical surgery could obtain a favorable long-term prognosis. Further investigation should focus on preoperative chemotherapy to eliminate peritoneal cancer cell. TRIAL REGISTRATION: This study is retrospectively registered.