Study confirms HRT increases ovarian cancer risk

EVIDENCE is mounting that HRT increases the risk of ovarian cancer, in addition to the well-established risk of breast cancer.

A Danish cohort study of 909,000 women found those who had used HRT had a 38% increased risk of developing ovarian cancer, compared to never-users, over an eight-year period. They had a 44% greater risk of epithelial ovarian cancer.  

The association remained regardless of the duration of use, formulation, oestrogen dose, regimen or progestin type, or the route of administration.

The absolute risk indicated approximately one extra ovarian cancer for every 8300 women taking hormone therapy each year. This equated to 140 extra cases over the eight-year follow-up.

“Even though this share seems low, ovarian cancer remains highly fatal, so accordingly this risk warrants consideration when deciding to use [HRT],” the authors said.

However, the risk declines with time since last use of HRT.

Professor Henry Burger, consultant at the Jean Hailes Foundation for Women’s Health, said the finding was in line with previous evidence.

“It’s a factor to think about, and in somebody who, for example, because of family history feels they are at higher risk... you would look out for it a bit more carefully,” he said.  

However, he said Denmark had a higher rate of ovarian cancers than many other countries, including Australia, where ovarian cancer is the sixth most common cause of cancer death in women, with 888 deaths in 2005, and a projected 1300 new cases in 2010.

A spokesperson for the National Breast and Ovarian Cancer Centre in Sydney agreed that the finding confirmed the link between HRT and ovarian cancer. 

JAMA 2009; 302:298-305