Estrogen receptor positive (ER+) cancers account for ~75% of all breast cancers. In ER+ the cancers respond to the presence or absence of estrogens (estrone, estradiol). Almost 65% of ER+ cancers are also progesterone receptor positive (PR+) meaning the cancer also responds to presence or absence of progesterone. In contrast, the HER2 strain of cancers involves an over production of the protein epidermal growth factor. HER2+ cancers are not amenable to hormone treatments and have not been linked to hormone levels, until recently.
A study published in Cancer Epidemiology Biomarkers and Prevention (Sieri et al. 2009) found that high circulating levels of testosterone were associated with an increased risk of breast cancer in menopausal women. The association was strongest for ER+ cancers, but was also present ER- cancers such as the HER2 strain. Though the association between testosterone and HER2+ cancers was not as strong as observed in the ER+ cancers, it was significant and merits additional research.
The role of androgens in breast cancer is controversial and there are differences between the hormone levels locally in the breast tissue versus those in circulation. Nevertheless, this study suggests that broader research, diagnostic and potentially treatment approach may be warranted.
To read this study go to: (Cancer Epidemiol Biomarkers Prev 2009;18 (1):169–76).