Progestins and breast cancer in hormone replacement therapy: how do they work, and what alternatives are safer

Abstract

In some studies, hormone replacement therapy (HRT) with estrogens and progestins has been associated with a higher risk of breast cancer than therapy with estrogens alone. However, depending on their nature, some progestins may be safer than others. This article analyzes the mode of action of progesterone in breast tissue and also the role of some progestins in the development of this pathology. Articles related to the subject were searched for and analyzed in Google Scholar, PubMed, Science, SciELO and Cochrane databases, introducing the following terms: hormone replacement therapy and breast cancer, progestins and breast cancer, progesterone receptor. Specifically, synthetic progestins medroxyprogesterone acetate, norethisterone, and levonorgestrel have been associated with an increased risk of breast cancer, but not natural progesterone, micronized oral progesterone, or dydrogesterone. Natural progesterone, micronized progesterone and dydrogesterone would be safer in HRT to prevent the development of breast cancer, which would be due to the greater specificity of their action.