CXCL8 and breast cancer: A comparison of parameter combinations against the comparative marker CA 15-3 revealed that, in the total study group and the luminal A subgroup of BC, combining CA 15-3 with CXCL1 (p = 0.008) and CA15-3 with CXCL1 and CXCL8 (p = 0.002) significantly improved the quality of the test.