In another study, blood was collected every 2 months for CTC analysis from EGFR-mutant NSCLC patients treated with erlotinib until disease progression and found that CTCs can be used to supplement the tissue-based EGFR mutation detection in lung cancer and to guide the precision treatment of EGFR mutation when appropriate tissue biopsy samples cannot be obtained for detection [12]. This evidence concerns the gene EGFR and non-small cell lung carcinoma.