Utility of Molecular Analysis of Peritoneal Fluid in Staging Laparoscopy of Advanced Esophagogastric Junction and Gastric Cancer Prior to Neoadjuvant Treatment

Purpose: Molecular analysis of peritoneal fluid in staging laparoscopy of gastric cancer is performed to improve the detection of free intraperitoneal tumor cells. Nevertheless, its significance is controversial, especially in patients with negative cytology but positive molecular analysis. The aim of this study was to analyze the sensitivity of molecular analysis and its prognostic value.

Methods: A retrospective analysis from April 2011 to October 2019 was performed. Cytology (Cyt) and molecular analysis were analyzed by real-time reverse transcriptase polymerase chain reaction (RT-PCR) of the carcinoembryonic antigen (CEA) and cytokeratin 20 (CK20) tumor makers.

Results: During the study period, 138 staging laparoscopies were performed. Macroscopic carcinomatosis was found in 12.3%. Of the remaining 87.7%, 9.9% were Cyt + and 11.6% were Cyt- RT-PCR + . Of the latter, 9 responded to chemotherapy and underwent radical surgery. The sensitivity of cytology and molecular analysis was 0.70 and 0.76, respectively (p = 0.67). The 2-year overall survival (OS) of Cyt- RT-PCR + vs. Cyt + was similar (p = 0.1). The 2-year OS of Cyt-RT-PCR + subgroup who underwent radical surgery vs. Cyt-RT-PCR- patients was similar (p = 0.69), but disease-free survival was shorter in the first group (p = 0.005).

Conclusion: Our results show that the sensitivity of molecular analysis is similar to that of cytology. The prognostic value of positive molecular analysis was similar to positive cytology in terms of 2-year overall survival, except in the subgroup of operated patients in whom the overall survival was similar to that of those with a negative molecular analysis, albeit with a shorter disease-free survival.