Women who have ever taken hormone therapy are at an increased risk of ovarian cancer compared with women who have never done so, regardless of duration of use, formulation, estrogen dose, regimen, or route of administration, according to the findings of a large, long-term study conducted in Denmark.

A team led by Lina Steinrud Mørch, MSc, analyzed various national Danish registers to assess the risk of ovarian cancer associated with hormone therapy use. The 909 946 women evaluated were all Danish, aged 50 to 79. After an average follow-up period of 8 years, 63% of the women remained nonusers of hormone therapy, 22% were previous users, and 9% were current users.

A total of 3068 ovarian cancers were detected during follow-up; 2681 were epithelial tumors. Compared with women who never used hormone therapy, current users had an overall increased risk of ovarian cancer of 38%. When considering only the 2681 cases of epithelial ovarian cancer, the relative risk was 44% higher for current users and 15% higher for previous users compared with never-users. The risk for ovarian cancer and epithelial ovarian cancer did not increase significantly with increasing durations of hormone therapy, but the risk of ovarian cancer declined with longer time since last use of hormone therapy.

The absolute risk indicated approximately 1 extra case of ovarian cancer for about 8300 women taking hormone therapy each year. “If this association is causal, use of hormones has resulted in roughly 140 extra cases of ovarian cancer in Denmark over the mean follow-up of 8 years, ie, 5% of the ovarian cancers in this study,” wrote the authors (JAMA. 2009;302[3]:298-305). “Even though this share seems low, ovarian cancer remains highly fatal, so accordingly this risk warrants consideration when deciding whether to use [hormone therapy].”

Source : Oncology Nursing News