Clinical Significance of Peripheral Blood CEA mRNA Expression in Gastric Cancer Patients Underwent Curative Resection

Recent advances in molecular technology have made it possible to detect small numbers of circulating tumor cells in the peripheral blood or bone marrow. Carcinoembryonic antigen (CEA) is an oncofetal antigen that is expressed in epithelial tumor cells. CEA mRNA may be a reliable marker for the detection of tumor cells in the peripheral blood of patients with epithelial cancer.

We analyzed the peripheral blood of 46 patients with gastric cancer who had undergone curative resection. The presence of CEA mRNA was serially monitored using RT-PCR (Preop, Post op 15 day, 2 months (m), 4 m, 6 m, 8 m, 10 m, 12 m). The clinical characteristics, serum CEA level and immunohistochemical staining of tumor tissue were also evaluated. Patients were followed up for 6 to 12 months.

There was no significant relationship seen between CEA mRNA RT-PCR positivity in the peripheral blood and sex, stage, serum CEA level or immunohistochemical staining for CEA antigen, During follow up,eight patients experienced recurrence; were positve for CEA mRNA RT-PCR recurrence was seen in 66.7% (6/9) of the patients who before clinical recurrence as compared to 5.4% (2/37) of patients who were negative (p=0.0002). Serial changes of CEA mRNA RT-PCR correlated with clinical recurrence; 100% in the positively converted group (3/3), 0% in the negatively converted group(0/18), 50% in all positive group (3/6) and 10.5% in all negative group (2/19) experienced recurrence, respectively.

RT-PCR analysis of CEA mRNA in the peripheral blood seems to be a promising tool for the early detection of micrometastatic circulating tumor cells in gastric cancer patients and may be useful in determining patients at high risk for recurrence. However, definitive correlation with recurrence certainly requires a longer follow up duration in further studies.