ERCC1 and neoplasm: Both tumor tissue samples and CTC samples detected 37 identical mutant genes, including PTEN, MET, EGFR, RET, FGFR3, etc. ERCC2 was only detected in CTC samples, while ERCC1, KRAS, PDGFRA, TPMT, IDH2 were only detected in tumor tissue samples (Figure 2B).