CTCs were detected based on EpCAM+ and CD45+ cells to exclude white blood cells. In the 98 lung cancer patients, the detection rate of CTCs (≥1 CTC) per 5 ml blood was 87.76%, the number of detections was 1–36, and the median was 2. By sequencing 72 lung cancer-associated genes, a high level of CNVs and gene mutations characteristic of tumour cells were identified. The gene discussed is PTPRC; the disease is lung cancer.