Breast cancer originates from the malignant transformation of epithelial cells within the ducts and lobules of the breast. A malignant cell is the result of the accumulation of consecutive mutations. Up or down regulation of different mutated genes will ultimately result in the heterogeneity of breast cancers . Some tumors will remain in situ and will never threaten the health of women. Other tumors will become invasive and ultimately metastasize and hence be fatal when not treated. The doubling time of tumor cells is estimated between 150 and 200 days .