Prognostic significance of the cytologic features of free cancer cells in the peritoneal cavity of patients with gastric cancer.

The aim of this study was to determine whether the cytologic features of cancer cells in the peritoneal lavage fluid from patients undergoing surgery for gastric cancer affect prognosis. A total of 141 patients with stage III-IV gastric cancer were enrolled in this study. Among 111 patients without peritoneal metastasis (P0), 43 were noted to have positive peritoneal cytology (P0/CY1). These patients were subclassified into two groups according to the cluster formation of cancer cells in the cytology specimen, namely, 17 with cluster formation and 26 without cluster formation. The clinicopathologic parameters and survival rates were compared between these two groups. Among the P0/CY1 patients, no significant difference in clinicopathologic features existed between patients with or without the cluster formation of cancer cells. However, the survival rate of patients without cluster formation was significantly higher than that of those with cluster formation. Furthermore, the survival curves of patients without cluster formation was similar to that of the P0/ CY0 patients with stage IV cancer. Subclassification according to the presence or absence of the cluster formation of cancer cells may be useful for predicting the outcome of patients with positive cytology after surgery for advanced gastric cancer.