PURPOSE: Cancer cells can be detected in bloods, lymph nodes or bone marrows by using reverse transcriptase-polymerase chain reaction (RT-PCR). We investigated to detect carcinoembryonic antigen (CEA) mRNA in peripheral blood by RT-PCR as a circulating tumor cell maker of gastric cancer patients.
MATERIALS AND METHODS: Gastric cancer patients were early gastric cancer with curative surgery (Group A, n=9), advanced gastric cancer with curative surgery (Group B, n 18) and relapsed or metastatic gastric cancer (Group C, n=13).
RT-PCR was performed to detect CEA mRNA expression in the peripheral blood mononuclear cells and we used Colo 201 cells as a positive control.
RESULTS: Seventeen patients (42.5%) were positive for CEA mRNA, whereas all the nine normal subjects were negative. There were significant differences between group A and C (p=0.041), group B and C (p=0.001) and between patients underwent curative surgery and metastatic gastric cancer patients (p 0.001) but not between A and B (p 0.326) for the positive rate of CEA mRNA.
CONCLUSION: Large number of gastric cancer patients showed positive CEA mRNA in peripheral blood suggesting that gastric cancer cells can metastasize into blood at early stage.