A matched case-control study of Triple negative vs. HER-2 positive (irrespective of hormonal status) breast cancer: two subtypes with high risk features and poor outcome.

Genetic profile studies of breast cancer identified a number of biologically different subtypes. These genetic subtypes are often surrogated by estrogen receptors (ER), progesterone receptors (PR) and HER2 status as measured by immunohistochemistry (IHC). Triple negative (TN) subtype is recognized to have high risk features and poor outcome. Over expression of the HER2 is also recognized as a poor outcome marker. The characteristics and outcome of HER2 positive tumours (irrespective of hormonal status) (HER2 HR+/-) identified by IHC have not addressed in the era of surrogate genetic subtyping. Therefore, we retrospectively compared the risk features and clinical outcome of patients with TN against these with HER2 HR+/- tumours.