The effects of therapy on estrogen receptors in breast cancer

The importance of estrogen receptors (ER) in predicting the results of therapy in advanced-stage breast carcinoma is now generally accepted. It is, therefore, important to know whether therapy itself, besides other factors, could affect ER status. The aim of the authors was to investigate this problem by reviewing the data from the literature. They have taken into account the effects of hormonal and/or chemotherapy and of radiotherapy, moreover, they have considered the importance of the time elapsed since the suspension of treatment. Hormonal therapy appears to be the kind of treatment more clearly correlated with a loss of ER: the authors have reported some hypotheses about the possible mechanisms of this action. The effect of chemotherapy is much less clear; the data about radiotherapy are few, unhomogeneous and, often, insufficient. Instead, it appears quite clear that ER tend to regain their original status after the suspension of therapy. More studies, are needed before any definitive conclusion can be drawn; it will be necessary to take into account also the possible effect of the different criteria for the preselection of patients. The actual data appear, anyway, to confirm the importance of routine receptor assay on breast tumors, especially after systemic treatment and independently of the kind of therapy itself.