When differentiating from other metastatic adenocarcinomas, in addition to selecting adenocarcinoma markers (MOC31, BerEP4, BG8, B72.3, CEA), organ‐specific markers such as estrogen receptor (ER), progesterone receptor (PR), GCDFP15, and mammaglobin for breast cancer, PAX8, PAX2, RCC, CD15 for renal cancer, and PAX8, ER, PR for ovarian cancer should also be included. This evidence concerns the gene ESR1 and breast carcinoma.