The gain in CDCP1 copy number in 38% of CDCP1-positive TNBC cases by FISH and the evidence that tumors with a high number of cells that express CDCP1 also bear many cells with alterations in CDCP1 support that a genetic gain in CDCP1 in this breast cancer subtype is involved in CDCP1 expression. Here, CDCP1 is linked to breast carcinoma.