FRIDAY, Oct. 21 (HealthDay News) -- High levels of sex and growth hormones are known to increase the risk of breast cancer, and it appears that other hormones circulating at high levels may also have a profound influence on the likelihood that a woman will develop postmenopausal breast cancer, according to research published online Oct. 21 in Breast Cancer Research.
Shelley S. Tworoger, Ph.D., of Brigham and Women's Hospital and Harvard Medical School in Boston, and colleagues analyzed hormone levels in blood samples collected from 265 women with breast cancer and 541 controls to evaluate the influence of multiple hormones on breast cancer risk; the blood samples were collected years before information about their breast cancer status was known.
The researchers found that the women with the highest estrogen or androgen levels had about two times the risk of developing postmenopausal breast cancer compared with those who had the lowest hormone levels. The presence of other hormones above the geometric mean increased risk with each additional hormone, especially for estrogen receptor (ER)-positive disease.
"Overall, the results of our study suggest that multiple hormones with high circulating levels substantially increase the risk of breast cancer, particularly ER-positive disease. Additional research should consider the potential impact of developing risk prediction scores that incorporate multiple hormones," the authors write.