Staging Laparoscopy with Peritoneal Lavage to Identify Peritoneal Metastases and Free Intraperitoneal Cancer Cells in the Management of Locally Advanced Gastric Cancer

Introduction: Gastric cancer often presents in advanced stage with a significant risk for peritoneal dissemination. Staging laparoscopy can be used to detect peritoneal carcinomatosis (PC +) and free cancer cells in peritoneal lavage cytology (CY +). The current study aimed to present the outcomes of staging laparoscopy and the prognosis of PC + and CY + in a Swedish high-volume center. Materials and methods: A cohort study including all consecutive patients with locally advanced gastric cancer who underwent staging laparoscopy between February 2008 and October 2022. The laparoscopy findings were categorized as PC +, PC-CY + (positive cytology without peritoneal carcinomatosis) or negative laparoscopy (PCCY-). The primary endpoint was overall survival (OS) stratified by laparoscopy findings. The secondary endpoint was OS within each laparoscopy finding group stratified by subsequent treatment. Results: Among 168 patients who underwent staging laparoscopy, 78 patients (46%) had PC-CY-, 29 patients (17%) had PC-CY + and 61 patients (36%) had PC +. Decreased OS was observed for both PC-CY + patients (aHR 2.14, 95% CI 1.13 -4.06) and PC + patients (aHR 5.36, 95% CI 3.21 -8.93), compared to PC-CY-. Patients with PCCY + who converted to PC-CY- after chemotherapy and underwent tumor resection seemed to have a better prognosis compared to patients with persisting PC-CY +. Conclusions: Staging laparoscopy is an important tool in the staging of locally advanced gastric cancer. Tumor resection for patients with PC-CY + who convert to PC-CY- may lead to improved survival for these patients.