Taken together, the higher level of circulating S100A8/A9 in the serum of breast cancer patients and the simultaneous elevation of CA15-3 might provide evidence for supporting the potential role of the S100A8/A9 heterodimer and CA15-3 in the prognosis, diagnosis and monitoring of breast cancer, although according to statistical analysis and the Roc Curve Plot S100A8/A9 probably is much better than CA15-3 because the results show that S100A8/A9 has 100% sensitivity and specificity for the diagnosis of breast cancer patients. This evidence concerns the gene S100A8 and breast carcinoma.