Common Menopause Therapy May Raise Cancer Risk

Ovarian cancer may be more likely if taking hormone replacement therapy for menopause

(RxWiki News) Hormone replacement therapy (HRT) is used by millions of women to treat menopause. HRT, however, has been shown to pose health risks, including increasing the chances of getting ovarian cancer.

Scientists recently reported that HRT for menopause was linked to an increased risk of developing two of the most common forms of ovarian cancer, even if a woman took the treatment for just a few years.

In the 1990s, HRT was a popular treatment for menopause. With this treatment, medication replaces female hormones that the body no longer produces. Its use declined, however, after researchers discovered that it may increase the risk of certain health problems, including heart disease, stroke and breast cancer.

Valerie Beral, MBChB (Bachelor of Medicine and Bachelor of Surgery), director of the Cancer Epidemiology Unit at the University of Oxford in England, and colleagues conducted this study.

“The definite risk of ovarian cancer even with less than five years of HRT is directly relevant to today’s patterns of use — with most women now taking HRT for only a few years,” said Professor Beral in a press release.

These researchers reviewed data from 52 investigations, involving a total of 21,488 women with ovarian cancer. The women were mostly from North America, Europe and Australia.

Professor Beral and her team found that women who had taken HRT for even a few years were about 40 percent more likely to develop ovarian cancer than those who had never taken HRT.

“For women who take HRT for five 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,” said coauthor Richard Peto, FRS, professor of medical statistics and epidemiology at the University of Oxford.

The research team noted that the risk of developing ovarian cancer fell over time after stopping treatment. Women who had used HRT for at least five years, however, still had a somewhat higher likelihood of getting ovarian cancer 10 years later.

Also, the raised risk was seen only for the two most common types of ovarian cancer (serous and endometrioid) and not for the two less common types (mucinous and clear cell).

The researchers estimated that about six million women in the United States and United Kingdom use HRT. In 2002, the Women’s Health Initiative (WHI) study showed that postmenopausal women who were using hormone replacement therapy that included both estrogen and progestin experienced an increased risk of breast cancer, heart disease, stroke, blood clots and urinary incontinence. This led to a sharp decline in HRT use in the early 2000s, according to the current study.

These researchers underscored that current guidelines on hormone replacement therapy from the US and the World Health Organization do not mention ovarian cancer. UK guidelines (which are currently being updated) mention only that ovarian cancer risk might increase with long-term HRT use.

This study was published Feb. 13 in The Lancet.  Funding was provided by the Medical Research Council and Cancer Research UK. The authors reported no conflicts of interest.

Review Date: 
February 12, 2015