Hormone Replacement Therapy (HRT)
may increase your risk of breast cancer.
According to the Women's Health Initiative (WHI) Postmenopausal Hormone Therapy Trials, estrogen-plus-progestin replacement therapy increases the risk of breast cancer, along with heart disease, stroke and blood clots.
The WHI clinical trials, launched in 1991, studied a group of 161,808 generally healthy postmenopausal women for the effects of HRT, diet modification and calcium and vitamin D supplement use on heart disease, fractures, and breast and colorectal cancer. Results from the trial on HRT, published in 2002, found that while the estrogen-only replacement therapy did not increase breast cancer risk, the risks far outweighed the benefits in the estrogen-plus-progestin arm. Overall, there was a 24% increase in the risk for breast cancer due to estrogen-plus-progestin.