The following factors have been associated with increased or decreased risk of developing breast and/or ovarian cancer in the general population. It is not yet known exactly how these factors influence risk in people with BRCA1 or BRCA2 mutations. In addition, a significant portion of hereditary breast cancers are not associated with BRCA1 or BRCA2 mutations.
No data have been reported to date regarding the effects of HRT on breast cancer risk among women carrying harmful BRCA1 or BRCA2 mutations, and only limited data are available regarding HRT use and ovarian cancer risk among such women. In one study, HRT use did not appear to affect ovarian cancer risk among women with BRCA1 or BRCA2 mutations.
When considering HRT use, both the potential harms and benefits of this type of treatment should be discussed carefully by a woman and her health care provider.