Carcinogenesis and Natural History of Breast Cancer

Abstract

The clinical presentation of breast cancer can range from microinvasive to highly metastatic. The vast majority of breast cancers belong to the class of carcinomas originating from the epithelium of the lobules and ducts of the gland, more specifically luminal cells (potentially secreting milk). Basal-like subtype breast adenocarcinomas – often negative for estrogen receptor (ER) and progesterone (PR) and HER2 receptor expression – have a genetic signature similar to myoepithelial cells that line tubules and lobules and are typical of tumors with BRCA1 deficiency [1, 7]. Invasive carcinoma is often associated with outbreaks of carcinoma in situ and with atypical hyperplastic lesions, suggesting that these premalignant lesions may represent precursor lesions of cancer. The less branched and more cellularized nulliparous type I lobes are more amenable to malignant transformation compared to the more differentiated multiparous type III lobe.