The classification of breast cancer is evolving. Historically, we classified breast cancers based on how they appear under the microscope and what growth patterns they make. This classification system is called “histological” and includes invasive ductal carcinoma, invasive lobular carcinoma and multiple other rarer types of breast cancer (medullary, mucinous, tubular, etc). This classification system does not provide much information regarding what the driving force of the cancer is, does not tell us what type of therapy is going to be most effective, and does not tell us much about prognsosis. In the last 3 decades, a more molecular classification has emerged (and continues to be refined). In the clinic, we now roughly classify tumors by the types of proteins the tumor expresses, including HER2, and the hormone receptors (ER and PR). This gives us more information about prognosis and guides treatment choices. For example, a tumor that is positive for ER and PR, negative for HER2 and is small, the best treatment after surgery/radiation is anti-hormonal therapy (tamoxifen and/or an aromatase inhibitor). Tumors that lack expression of all three proteins are termed “triple negative” and tend to be more aggressive, often requiring chemotherapy. Inflammatory breast cancer is a clinical diagnosis (not a molecular or histological diagnosis) that is made when a patient has a very rapid development (days to weeks) of a red, hot, swollen breast. It is rare (1% of all breast cancer) and is most commonly HER2+ or triple negative and requires urgent treatment with chemotherapy.
Question by: Herbaldale
(Complementary Care Expert (Verified)