A study published in this monthÃs Journal of the National Cancer Institute links high levels of male hormones (androgens) to an increased risk in young women of developing breast cancer. Prior studies produced similar results with respect to postmenopausal women. Although androgens are normally present in women, as a rule, the levels are far lower than those found in men.
The new study, which involved 1,096 premenopausal women, found that as testosterone and androstenedione levels rose, the likelihood of developing breast cancer increased significantly. The results showed that, in women under 40, the risk of developing breast cancer over a 10-year period ranged from 1.5% for those with the lowest testosterone levels to 2.6% for those with the highest levels.
The research team concluded that the study "provides strong evidence that the risk of breast cancer among premenopausal women is directly related to circulating levels of testosterone and androstenedione." Further studies are needed to see if this risk can be lowered by lifestyle changes or other interventions.