Tumor-positive peritoneal cytology in patients with gastric cancer is associated with poor outcome: A nationwide study

The clinical significance of tumor-positive peritoneal cytology (CYT+) in gastric cancer (GC) patients is unclear. This nationwide cohort study aimed to i) assess the frequency of cytological analysis at staging laparoscopy; ii) determine the prevalence of CYT+GC; and iii) compare overall survival (OS) in CYT+ patients versus those with (PM+) and those without (PM-) macroscopic peritoneal disease. All patients diagnosed with cT1–4, cN0–2 and M0 or synchronous PM GC between 2016–2021 were identified in the Netherlands Cancer Registry database and linked to the nationwide pathology database. A total of 4397 patients was included, of which 40 % underwent cytological assessment following staging laparoscopy (863/1745). The prevalence of CYT+ was 8 %. A total of 69 patients had CYT+(1.6 %), 789 (17.9 %) had PM+ and 3539 (80.5 %) had PM- disease. Hazard ratio for OS in CYT+ versus PM+ was 0.86 (95 %CI 0.64–1.17, p-value=0.338), and in PM- versus PM+0.43 (95 %CI 0.38–0.49, p-value