In the Luminal A BC patient subgroup, the highest SE was shown by the combined of the three parameters CXCL1 + CXCL8 + CA 15-3 (98%), while in the Luminal B BC patient subgroup—for two combinations with equal values of 94%—CXCL8 + CA 15-3 and CXCL1 + CXCL8 + CA 15-3. The gene discussed is CXCL8; the disease is breast cancer.