Objective: To investigate the expression of carcinoembryonic antigen (CEA) and cytokeratin19 (CK19) mRNAs in peripheral blood of patients with lung cancer and their correlation with staging, treatment response and prognosis.
Methods: CEA and CK19 mRNAs in peripheral blood were detected by Taq Man reverse transcriptase-polymerase chain reaction (RT-PCR) in 78 patients with lung cancer before and after treatment, 30 patients with benign lung diseases and 30 healthy subjects. Serum CEA and CYFRA21-1 levels were also measured by enzyme linked immunosorbent assay (ELISA) in the 78 patients with lung cancer before treatment. The patients were followed for 2 years.
Results: The positive rates of CEA mRNA and CK19 mRNA in patients with lung cancer were 69.2% (54/78) and 62.8% (49/78), respectively, which were significantly higher than those in patients with benign lung diseases and the healthy controls (P < 0.01). The positive rate of CEA mRNA was the highest in adenocarcinoma, while the positive rate of CK19 mRNA was the highest in squamous cell carcinoma. There was no statistically significant difference among different stages (P > 0.05), The positive rates of CEA mRNA and CK19 mRNA were higher than those of serum CEA and CYFRA21-1. The positive rates of CEA mRNA and CK19 mRNA decreased significantly after surgical operation, but there was no significant change after chemotherapy. The median survival time (MST) for patients with a positive CEA mRNA before chemotherapy was shorter than those with a negative CEA mRNA (8.5 month and 11.7 month, respectively). The MST for patients with a positive CK19 mRNA before chemotherapy was shorter than those with a negative CK19 mRNA (8.9 month and 12.3 month, respectively). The rate of relapse and metastasis was higher in patients (29.4%) with a positive CEA mRNA preoperatively than those with a negative CEA mRNA (7.7%). The rate of relapse and metastasis was also higher in patients with a positive CK19 mRNA preoperatively (18.8%) as compared to those with a negative PCR result (7.1%).
Conclusions: CEA and CK19 mRNAs can be used as markers in the detection of tumor micrometastases in lung cancer, and in evaluating surgical response and prognosis. The results suggest that the gene markers are better than the serum ones, and therefore may be useful for the early diagnosis of lung cancer.