Results from the study, show that over five years there is one extra case of ovarian cancer in every 2,500 women who take HRT. And for every 3,300 women who take HRT, there will be one additional death from ovarian cancer.
The researchers, who are largely funded by Cancer Research UK, estimate that use of HRT since 1991 has resulted in an extra 1,300 cases and 1,000 deaths from ovarian cancer. The study also suggests that a woman’s risk of ovarian cancer returns to a normal level within a few years of stopping HRT. The research showed that the risk of ovarian cancer was increased regardless of which kind of HRT the women were taking.
Previous results from the study have linked the use of HRT with breast and endometrial cancer, a cancer of the womb lining.
The overall incidence of these three cancers in women who take HRT is 31 cases for every 1,000 women over five years. This compares with 19 cases in women who have never taken HRT.
“This study clearly shows that taking HRT increases a woman’s chance of getting ovarian cancer and her chances of dying from the disease,” said professor John Toy, Cancer Research UK’s medical director.