Peritoneal cytology in patients with gastric cancer exposed to the serosa--a proposed new classification based on the local and distant cytology.

BACKGROUND/AIMS: The clinical impact of the cytology of intraperitoneal samples taken from the local and distant sites was examined in patients with gastric carcinoma.
METHODOLOGY: Intraoperative peritoneal cytology was evaluated in 149 patients with gastric cancer invading the serosa but no metastasis to the peritoneum (macroscopic P0), the liver (H0), or distant organs (M0). Lavage samples were collected from the Douglas pouch and the left subphrenium (distant sites). Both lavage and smear samples were taken from the serosal surface invaded by the tumor (local).
RESULTS: Positive peritoneal cytology was found in 33 of 149 patients (22.1%). All patients were categorized into three groups: Group I had negative cytology (n = 116, 77.9%), Group II had positive local cytology (n = 14, 9.4%), and Group III had positive distant cytology irrespective local status (n = 19, 12.8%). By multivariate analysis, peritoneal cytology was the only significant independent factor affecting survival. Median survival was significantly shorter in Group III (400 +/- 177 days) than in Group I (2228 +/- 599 days). The peritoneal recurrence-free interval was significantly shorter in Group II than in Group I.
CONCLUSIONS: The extent of peritoneal seeding was variable and appeared to have a significant impact on prognosis. Peritoneal cytology should be evaluated not only at a distant site, but also locally to identify the subset of patients with limited peritoneal dissemination.