Table 7: Blood androgen levels and breast cancer risk

Introduction: Androgens are hormones, such as testosterone, that are important in sexual development in both men and women. In women, androgens are produced in small amounts by the ovaries and the adrenal glands. Similar to higher blood estrogen levels, higher amounts of androgens in the blood may be linked to an increased risk of breast cancer in women.

Testosterone

Of the androgens that have been studied in relation to breast cancer risk, the most data are available for testosterone. Studies show higher blood levels of testosterone may increase the risk of breast cancer in postmenopausal women. And, although findings are limited, there is some evidence that higher blood levels of testosterone may also increase breast cancer risk in premenopausal women.

Blood androgens and postmenopausal hormone use

Most of the studies below excluded women who were taking postmenopausal hormones at the time of the blood collection. Certain types of postmenopausal hormones might mask the full effect natural blood testosterone levels have on breast cancer risk. By looking only at women who do not take (or who have never taken) postmenopausal hormones, researchers may see more clearly how blood androgen levels affect breast cancer risk. 

Learn about the strengths and weaknesses of different types of studies.

See how this risk factor compares with other risk factors for breast cancer.

Study selection criteria: Nested case-control studies, case-control studies and pooled analyses with at least 100 breast cancer cases.

Table note: Odds ratios above 1 indicate increased risk. Odds ratios below 1 indicate decreased risk.

Risks related to total testosterone levels (unless noted) are shown in this table. Although free testosterone and/or bioavailable testosterone may also be related to breast cancer risk, many studies have not measured these and data are limited at this time.  

*ER+ = Estrogen receptor-positive

ER- = Estrogen receptor-negative

* Results for blood levels of bioavailable testosterone.

† For testosterone blood levels measured in the luteal phase of a woman’s menstrual cycle. Testosterone blood levels as measured in the early follicular stage, the risk was not significant, RR=1.8 (0.9-3.4).

‡ For testosterone blood levels measured in the luteal phase of a woman’s menstrual cycle. Testosterone blood levels as measured in the early follicular stage, the risk was also not significant, RR=0.45 (0.17-1.19).

References  

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Updated 09/15/11