Objective：To investigate the clinical significance of CK20 mRNA detection in peritoneal fluid of gastric cancer patients.
Methods：CK20 mRNA expressions in ascitic or peritoneal lavage fluid of 49 patients with gastric cancer were detected by real-time fluorescent quantitative reverse transcription polymerase chain reaction (FQ-RT-PCR), and 10 non-tumor patients undergoing surgery during the same period were used as control.  Further, the results were analyzed with their clinicopathological data and follow-up results.
Results：The positive rate of CK20 mRNA in ascitic and peritoneal lavage fluid was 50.00% and 35.90%, respectively, which showed no significant difference (P＞0.05). The overall positive rate of CK20 mRNA was 38.78% in gastric cancer group, while no positive expression was detected in control group. The positive rate of CK20 mRNA expression was significantly higher than the positive rate of peritoneal cytology examination (10.20%) (P＜0.05). The expression of CK20 mRNA was related to whether or not lymph node metastasis and the depth of tumor invasion (both P＜0.05), but was irrelevant to the degree of differentiation (P＞0.05). The average survival time of the patients with CK20 mRNA positive expression was significantly decreased compared with the negative ones (20.95 months vs. 33.24 months) (P＜0.01).
Conclusions：The detection of CK20 mRNA in ascites or peritoneal washings can diagnose the peritoneal micrometastasis in the early-stage, and is useful for estimating prognosis and guiding treatment.