Can hormone replacement therapy cause ovarian cancer?

Synthetic hormones estrogen and progestin – used to treat menopause symptoms – have been linked to a higher risk of ovarian cancer, according to a new study published in The Lancet. Hormone replacement therapy (HRT) has previously been associated with heart disease, stroke, and breast cancer. Oxford University organized a meta-analyzed 52 published and unpublished studies that involved more than 21,000 women and found that “for women who take HRT for 5 years from around age 50, there will be about one extra ovarian cancer for every 1,000 users and one extra ovarian cancer death for every 1,700 users, ” lead researcher Sir Richard Peto said. More than 100 researchers from all over the world participated in the study, known as the Collaborative Group on Epidemiological Studies of Ovarian Cancer.

This, “the first big study like this to really come out and say ovarian cancer is an issue,” as assistant professor of obstetrics, gynecology and reproductive science and a minimally invasive gynecological surgeon Dr. Taraneh Shirazian – who was not involved in the study – described it to CBS News, will surely contribute to the decline in use that HRT has experienced since the start of the 2000s decade. On the other hand, approximately 6 million women in the United States and the United Kingdom continue to use hormones. Ovarian cancer is not generally listed by doctors among the potential risks – which include heart disease, stroke, blood clots, osteoporosis and breast cancer.  “I wasn't actually given any information in regards to any breast cancer risk or ovarian cancer risk,” Theresa Chaffey, from Bournemouth, told BBC News. “Hearing the news today is very worrying because of actually being on HRT for so long and with GPs continually saying I need to stay on it for my bones as well as any symptoms.”

Though short-term use is thought to be less risk, Peto said this was “simply not true.” “It's a risk, about a million women in this country have HRT and 1,000 will get ovarian cancer from it,” Peto told “If it were me and I had really bad symptoms, I'd worry more about those than any possible risk.” Study author professor Dame Valerie Beral added that “the definite risk of ovarian cancer even with less than 5 years of HRT is directly relevant to today's patterns of use - with most women now taking HRT for only a few years - and has implications for current efforts to revise UK and worldwide guidelines.” Hormone replacement therapy is a godsend for many women, though. “My life would be unbearable if I don't have HRT and for a number of other women who suffer severe menopausal symptoms it is the same. We have to weigh up the quality of life alongside the risks, and therefore HRT is a risk we'd rather take than have no life,” Val Weedon from Chatham in Kent said.

Shirazian agrees: “there’s nothing quite like estrogen. If my patient has been trying a number of other things and these things have not been helping and they really have significant symptoms that affect their daily life, I would consider hormone replacement.” According to professor Montserrat Garcia-Closas from the Institute of Cancer Research in London, though the study “shows really very convincingly that there is an association” between HRT and ovarian cancer, “it’s a modest increase on a relatively uncommon cancer.” So it becomes a question of “the benefits of hormone replacement therapy weighed against that risk ratio for developing ovarian cancer,” as Shirazian puts it.