A sweeping new analysis adds to the evidence that many women who take hormone therapy during menopause are more likely to develop breast cancer — and may remain at higher risk of cancer for more than a decade after they stop taking the drugs.
The study, published Thursday in the Lancet, looked at data from dozens of studies, including long-term data on more than 100,000 women who developed breast cancer after menopause. Half of those women had used what’s known as menopausal hormone therapy, or MHT. The longer women took the medicine, the more likely they were to develop breast cancer. Experts say the findings could shape how women and their health care providers decide how to manage symptoms of menopause.
“This is a consensus of many researchers and many studies all around the world. These are important new results,” said said Valerie Beral, a cancer epidemiologist at the University of Oxford and one of the lead authors of the new study.
Women have long been prescribed synthetic versions to replace the hormones that decline during menopause. The medications — usually delivered in a pill, but sometimes in a patch, gel, or injection — provide women either estrogen or a combination of estrogen and progesterone. For many women, they help to tamp down symptoms of menopause, including osteoporosis.
For years, research has suggested a potential link between MHT and an increased risk of breast cancer. In 2002 and 2004, the Women’s Health Initiative released reports that showed women who used combination MHT were more likely to develop breast cancer. MHT use fell after the reports received widespread coverage. That was followed by a decline in breast cancer rates.