Abstract:
Objective : To investigate the expression of carcinoembryonic antigen (CEA) mRNA in the peripheral blood of patients with gastric cancer and its correlation with pathological factors, chemotherapy response and prognosis.
Methods : The expression of CEA mRNA in peripheral blood was detected with TaqMan reverse transcriptase-polymerase chain reaction (RT-PCR) in 58 patients with gastric cancer before and after chemotherapy and in 20 healthy subjects. Serum CEA protein levels were also measured by chemiluminescent immunoassay before treatment. The patients were followed up for 2 years.
Results : The positive rate of CEA mRNA in patients with gastric cancer was 56.9% (33/58), significantly higher than in the healthy controls (P <0.001). Univariate analysis revealed that the depth of tumor invasion (
P =0.035), lymphatic metastasis (
P = 0.042), distant metastasis (
P =0.006) and serum CEA protein levels (
P =0.001) were related to the CEA mRNA expression in peripheral blood. Multivariate logistic regression showed that lymphatic metastasis and serum CEA protein levels were independent factors for CEA mRNA expression. The positive rate of CEA mRNA was higher than that of serum CEA protein. The detection rates of chemiluminescent immunoassay and TaqMan RT-PCR for CEA were consistent (88.9%). The positive rate of CEA mRNA did not decrease significantly after 2 cycles of chemotherapy (
P>0. 05), but the positive rate of CEA mRNA in patients with no response to chemotherapy was significantly higher than that in patients who responded. The 1-year survival rate in patients with detectable CEA mRNA before chemotherapy was lower than that in patients with no detectable CEA mRNA, and the difference between the two groups was significant (
P =0. 002).
Conclusion : CEA mRNA can be used as a marker in the detection of tumor micrometastasis in gastric cancer patients, and regular quantification of CEA mRNA in peripheral blood may be important in evaluating chemotherapy response and prognosis. Lymphatic metastasis and serum CEA protein levels appeared to be highly correlated with gastric cancer hematogenous metastasis. Expression of CEA mRNA is a better marker than serum CEA protein expression and therefore may be useful for early diagnosis of gastric cancer.