The increase in risk was found regardless of the hormone dose or formulation, whether hormones were taken by mouth, transdermal patch, or vaginally, or whether the treatment included just estrogen or estrogen and progestin, the researchers say.
The study confirms earlier research linking hormone therapy and ovarian cancer, but the new study is believed to be the largest and most detailed study to date on the topic, says the study's lead author Lina Morch, a researcher at Rigshospitalet, Copenhagen University in Denmark, WebMD reports.
Women who took hormone replacement therapy after menopause had a sharply increased risk of ovarian cancer, researchers in Denmark are reporting.
In a study of more than 900,000 Danish women ages 50 to 79, the scientists found 140 extra cases of ovarian cancer linked to hormone treatment over eight years. That translated to a 38 percent greater risk of contracting the disease, compared with women who did not receive the therapy.
Hormone therapy accounted for 5 percent of the cases of ovarian cancer in the study period, the researchers reported in The Journal of the American Medical Association, New York Times reports.
Menopausal women who took hormone replacement therapy increased their risk of ovarian cancer by 38 percent, Danish researchers reported on Tuesday.
The study of more than 900,000 Danish women aged 50 to 79 found about one extra ovarian cancer for roughly 8,300 women taking hormone therapy each year.
At the time they got sick, 9 percent of the women were taking hormone therapy, 22 percent were previous users and 63 percent did not take it. The researchers calculated that current hormone use conferred a 38 percent higher risk of contracting the disease compared to non-users over the eight-year study, Reuters reports.