Background: Peritoneal lavage cytology is an excellent prognostic determinant but lacks sensitivity. Quantification of carcinoembryonic antigen (CEA) mRNA in peritoneal washes by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) was found to be a more sensitive method to detect free cancer cells. It may be beneficial to explore, by the same method, a sample of the omentum, which is known to harbor cancer cells before the establishment of gross peritoneal metastasis.
Methods: Greater omentum and peritoneal washes were obtained from 90 gastric carcinoma patients during laparotomy. The CEA mRNA levels in these materials were quantified using a real-time RT-PCR system with hybridization probes. The significance of CEA mRNA levels in both materials, as a predictive factor of peritoneal metastasis, was explored by univariate and multivariate analyses.
Results: After a median follow-up of 718 days, 13 patients had clinical evidence of peritoneal metastasis. Under the assumption that these patients had free cancer cells in the peritoneal cavity, the sensitivity and specificity of conventional cytology for the detection of these cells were 31% and 100%, respectively. The sensitivity and specificity of the CEA mRNA levels extracted from the peritoneal washing samples were 77% and 94%, while those of the omentum were 46% and 90%. Multivariate analysis, with the diagnosis of peritoneal metastasis as an endpoint, revealed that CEA mRNA level in the peritoneal washes was the only significant risk factor.
Conclusion: Quantitative RT-PCR of peritoneal washes remains the first choice as a tool to sensitively predict intraperitoneal recurrence in gastric carcinoma patients.