Role of progesterone receptor in luminal breast cancers

Abstract

In clinical practice luminal B breast tumours are characterised by having estrogen receptor, the absence of HER2, and a lack or low levels of progesterone receptor, optionally with a high index of Ki67. However, the actual molecular classification of luminal cancers is based on differences in the expression of the whole panel of genes, not only those related to the above mentioned receptors. Luminal B cancers, are in fact, estrogen receptor positive tumours, but with worse outcome. Recently, it is frequently suggested that the luminal B tumours are a group in which the func­tion of the estrogen receptor is not critical and other pathways are over-activated, which are related with growth factors: for example epithelial (EGF), insulin-like (IGF ) or fibroblast (FGF). Surprisingly there are also many interactions between various growth factors with estrogen receptor. This paper presents the heterogeneity of breast cancer. It is also a starting point for further research.