Objective: We tested whether circulating tumor cells can be detected in the peripheral blood of patients with resectable non-small-cell lung cancer (NSCLC) by reverse transcriptase-polymerase chain reaction (RT-PCR) of carcinoembryonic antigen (CEA) mRNA.
Methods: We assayed for CEA mRNA by RT-PCR in the peripheral blood, taken at the time of diagnosis before surgical intervention and again 2 to 3 weeks postoperatively, from 103 patients with NSCLC who underwent curative lobectomy. Blood samples taken from 15 patients with interstitial pulmonary fibrosis who underwent an open-lung biopsy and from 32 healthy subjects served as controls.
Results: No control samples were positive for CEA by RT-PCR. Sixty-two (60%) of the preoperative blood samples from the 103 patients with NSCLC were positive. Of these 62 samples, 27 (44%) remained positive even after surgical intervention, whereas the remaining 35 samples (56%) became negative. The incidence of positive CEA mRNA correlated highly with pathologic TNM stage of disease in both the preoperative and postoperative blood samples.
Conclusions: Many patients with resectable NSCLC have detectable levels of circulating cells expressing carcinoembryonic antigen even after surgical intervention. Such patients may have a higher rate of relapse.