Adapted from the NCI Cancer Bulletin.
Women who have taken hormone therapy are at a higher risk of developing ovarian cancer than women who have not, according to a nationwide study involving nearly 910,000 women in Denmark. The findings, which confirm and extend the results of previous studies, suggest that the risk of ovarian cancer should be a factor when women consider using hormone therapy to treat postmenopausal symptoms. The study is reported in the July 15, 2009 issue of the Journal of the American Medical Association (see the journal abstract).
Lina Steinrud Mørch of Copenhagen University and her colleagues used detailed information from national registries to detect an increased risk of ovarian cancer among former and current hormone users, compared with non-users. A woman's risk did not seem to depend on the type of hormones, the duration of use, or the mode of administration. The findings translate into about 1 extra ovarian cancer per approximately 8,300 women taking hormone therapy each year.
Since the Women's Health Initiative reported in 2002 that combination hormone therapy (estrogen plus progestin) was associated with an increased risk of breast cancer, several studies have linked estrogen-alone therapy to the risk of ovarian cancer. There have also been hints of an increased risk from combination therapy, and these are now confirmed.
"Here we see that combination therapy had essentially the same amount of increased risk as estrogen-alone therapy," said Dr. Garnet Anderson, an ovarian cancer researcher at the Fred Hutchinson Cancer Research Center. The results, she added, are not likely to alter the current guidelines on hormone therapy, which urge women to use the smallest possible dose for the shortest time period.
Hormone therapy may have caused approximately 140 extra cases of ovarian cancer in Denmark during the study period, or 5 percent of the ovarian cancers. "Even though this share seems low, ovarian cancer remains highly fatal, so accordingly this risk warrants consideration when deciding whether to use hormone therapy," the authors concluded.