Prognostic significance of peritoneal minimal residual disease in gastric cancer detected by reverse transcription-polymerase chain reaction

Abstract

Background: A sensitive method for detecting minimal residual disease in the peritoneal cavity by quantifying carcinoembryonic antigen (CEA) mRNA using real-time quantitative reverse transcription-polymerase chain reaction (RQ-RT-PCR) was developed. The clinical value of the method for predicting peritoneal recurrence in patients with gastric cancer was evaluated. Method: A total of 195 patients with gastric cancer and 20 with asymptomatic cholecystolithiasis were included in the study. CEA mRNA expression in peritoneal washings (p-CEA mRNA) was measured by RQ-RT-PCR and normalized to glyceraldehyde-3-phosphate dehydrogenase mRNA expression. The cut-off level of p-CEA mRNA for gastric cancer was determined by examining p-CEA mRNA levels in patients with asymptomatic cholecystolithiasis. Results: Fifty-five (28.2 per cent) of the 195 patients were p-CEA mRNA positive. The rate of p-CEA mRNA positivity correlated significantly with clinicopathological factors. In 163 patients who underwent curative surgery, overall survival and disease-free survival were significantly poorer in p-CEA mRNA-positive patients than in p-CEA mRNA-negative patients (P < 0.001). Cox regression analysis revealed that only p-CEA mRNA was a significant independent prognostic factor (P = 0.034). Multivariate logistic regression analysis showed that p-CEA mRNA was a significant independent risk factor for peritoneal recurrence (P = 0.027). Conclusion: These results suggest that p-CEA mRNA is a reliable prognostic factor and predictor of peritoneal recurrence in gastric cancer.