Circulating tumor cell levels and carcinoembryonic antigen: An improved diagnostic method for lung adenocarcinoma

The aim of this study was to determine a correlation between benign and malignant lung solitary pulmonary nodules (SPN), and analyze the association between circulating tumor cell (CTC) levels and different subtypes of lung adenocarcinoma.

A total of 200 patients (80 with SPNs and 120 diagnosed with lung cancer) were included in the study. The CTC levels were quantified by identifying the folate receptor on the surface of tumor cells; clinical tumor specific markers were detected by biochemical immunization. The content of peripheral blood CTCs in benign and malignant lung SPN patients was detected and the differences in preoperative CTC levels in different pathological subtypes were analyzed. Based on the collected data, receiver operating characteristic curves were calculated and the rate of lung cancer was predicted.

The peripheral blood CTC levels in patients with malignant lung SPNs were higher than in patients with benign SPNs. The maximum nodule diameter, carcinoembryonic antigen, and CTC levels were independent risk factors for malignant lung SPNs. The peripheral blood CTC levels in patients with stage III-IV lung adenocarcinoma were higher than in stage I-II patients. The peripheral blood CTC levels in patients with microinvasive and invasive adenocarcinoma were higher than in adenocarcinoma in situ patients. The CTC levels in the peripheral blood of patients with maximum tumor diameter > 2 cm were higher than in patients with tumors < 2 cm.

The detection of CTCs can be used as a biomarker for screening SPNs and diagnosing early-stage lung cancer. Using the combination of CTC levels and CEA significantly improves the efficacy of lung adenocarcinoma diagnosis.