Evaluation of intraoperative intraperitoneal cytology for advanced gastric carcinoma

Objective: We evaluated intraperitoneal cytology during surgery as a significant predictor of survival and tried to establish strategies for preventing peritoneal carcinomatosis. Methods: The study included 236 patients with gastric carcinoma macroscopically invading the serosa who underwent intraperitoneal cytological examination during surgery. In the 215 resected patients, the relationship between cytological positivity for cancer cells and various clinicopathologic features was analyzed. Additionally, postoperative survival was assessed in relation to the positivity of intraoperative cytology. Results: Cancer cells were positive [Cy(+)] in 78 (33.1%) of 236 patients who underwent cytological examinations. Among 73 patients with peritoneal metastases, 53 patients (72.6%) were Cy(+), as were 25 (15.3%) of the 163 patients without peritoneal metastases. Multivariate analysis indicated that peritoneal metastasis (p = 0.0001) and the depth of tumor invasion (p = 0.0069) were significant factors correlated with Cy(+). Among patients with curative surgery, the 5-year survival rate of the Cy(+) group was 22.2%, which was worse (p = 0.0004) compared with that of the Cy(-) group (60.9%). Among Cy(+) patients, the survival rate of the group treated with intraperitoneal administration of mitomycin C (MMC) and OK-432 was better (p = 0.0108) than that of the historical control group. Conclusion: These results suggest that intraperitoneal cytological examination can be a significant prognostic factor for gastric carcinoma with serosal invasion. In addition, dissemination of cancer cells in the peritoneum may be controlled by intraperitoneal immunochemotherapy with MMC and OK-432.