Androgens (such as testosterone) are natural hormones. They 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.
Higher levels of androgens in the blood may be linked to an increased risk of breast cancer in women [45-48].
Most studies on androgens and breast cancer risk have looked at the androgen testosterone.
In postmenopausal women, studies show higher levels of blood testosterone increase the risk of breast cancer [45-47].
A pooled analysis of data from five studies found that higher levels of blood testosterone may modestly increase breast cancer risk before menopause .
Studies in premenopausal women are a challenge because blood hormone levels vary over the menstrual cycle.
For a summary of research studies on blood androgen levels and breast cancer risk, visit the Breast Cancer Research Studies section.