WASHINGTON — Add another risk to hormone therapy after menopause: benign breast lumps.
One type of hormone therapy — estrogen plus progestin — already is known to increase the risk of breast cancer. But a major study of women able to use estrogen alone didn't find that link.
Researchers reported a new wrinkle Tuesday: Those estrogen-only users doubled their chances of getting noncancerous breast lumps. That's a concern not only because of the extra biopsies and worry those lumps cause, but because a particular type — called benign proliferative breast disease — is suspected of being a first step toward developing cancer 10 years or so later.
About one in five women undergo a breast biopsy within a decade of starting annual mammograms, and most abnormalities turn out to be benign.
The latest work, published in the Journal of the National Cancer Institute, re-examines data from the landmark Women's Health Initiative. Only women who have undergone hysterectomies are able to use estrogen-only therapy, and the WHI originally included more than 10,000 of those women, who were given either estrogen or a placebo and tracked for about seven years.
A team led by Dr. Tom Rohan of the Albert Einstein College of Medicine in New York identified 232 cases of benign proliferative breast disease. The estrogen group had twice the risk of developing the abnormality compared with the placebo group.