Currently, molecular, prognostic, and predictive factors that have been incorporated into the mammary pathological evaluation routine include: TNM staging, tumour size, the presence of lymph node alterations, histological type and grade, expression of hormone receptors such as oestrogen receptor (ER) and progesterone receptor (PR), amplification of the epidermal growth factor 2 gene (HER-2/Neu), overexpression of Bcl-2, mutations in p53, BRCA1 and BRCA2 genes, expression of cathepsin D, cyclin D1, and protein levels of Ki67 antigen (a cell proliferation marker). This evidence concerns the gene PGR and neoplasm.