Conventional cytology vs. immunocytochemistry of intraoperative peritoneal washes in gastric cancer patients subjected to gastrectomy: clinical correlates and association with overall survival.

Background: The aim of this study was to verify if positive results yielded with conventional cytology and immunocytochemical analysis of peritoneal washes correlate with established prognostic factors and overall survival (OS) in gastric cancer patients.
Methods: The study included the data of 271 gastrectomized patients. Peritoneal washes of 131 (48.3%) patients were examined by means of conventional cytology, and material from 140 (51.7%) subjects treated surgically after this date was subjected to immunocytochemical analysis.
Results: Free cancer cells (FCCs) were detected significantly less often in patients from conventional cytology group than in those from immunocytochemistry group (4.6% vs. 12.1%). Positive result of immunocytochemical analysis was significantly more often associated with presence of pT3/4 tumor (94.1% vs. 60.2%), lymph node ratio ≥0.2 (82.4% vs. 43.1%) and involvement of blood vessels (64.7% vs. 28.5%). Median OS in patients with immunocytochemical evidence of FCCs in peritoneal washes was significantly shorter than in those without (11 vs. 45 months). Moreover, the two groups differed significantly in terms of 5- (0% vs. 43.1%) and 10-year OS rates (0.0% vs. 29.3%).
Conclusions: In contrast to conventional cytology, immunocytochemically documented presence of FCCs in peritoneal washes correlates with established prognostic factors and OS in gastric cancer patients.