ESR1 and neoplasm: Additionally we decided to analyze nine markers of well-known tumor specificity (ERBB2, ESR1, PGR, PLAT, SCGB2A1, SCGB2A2, SERPINE1, SERPINE2 and TFF1) and six candidate markers for CTC detection that were previously identified by our research group (COL3A1, GHR, CALB1, LPHN1, FN1 and EDNRA) [27].