Source: Heart  |  Posted 9 years ago

Postmenopausal women who use long term estrogen replacement therapy (ERT) are at greater risk of developing ovarian cancer than are women not using hormone replacement therapy (HRT).

Researchers from the National Cancer Institute in Bethesda, Maryland, United States, followed 44,241 women in this study for approximately 20 years. "Women who used ERT, particularly for 10 or more years, were at significantly increased risk of ovarian cancer," they say.

"We observed an elevated risk of ovarian cancer among long-term ERT users with hysterectomy and among ERT users without hysterectomy who had switched to estrogen-progestin replacement therapy (EPRT)."

They point out that women using short-term EPRT only were not found to be at increased risk, "but risk associated with EPRT remains unclear."

The investigators, led by Dr. James Lacey Jr,. suggest use of ERT and EPRT affects both breast and endometrial cancer risk differentially and may do the same for ovarian cancer. They say additional data is needed, particularly on duration, dose and regimen.

Participants in the 1979 to 1998 cohort study had also participated in the US Breast Cancer Detection Demonstration Project. The US-wide breast cancer-screening program included women attending 29 clinics. Mean age at start of follow-up was 56.6 years.

Three hundred and twenty nine women were found to develop ovarian cancer.

The researchers found ever-use of ERT was significantly associated with ovarian cancer in time-dependent analyses adjusted for age, menopause type and oral contraceptive use. The rate ratio (RR) was 1.6.

Increased duration of ERT use was significantly associated with risk. The RR for 10 to 19 years of use was 1.8; the RR for 20 or more years of use was 3.2.

A 7 percent increase in RR for each year of ERT use was reported. Significantly elevated RRs with increased duration of use were found across all strata of other ovarian cancer risk factors. This included hysterectomy.

The researchers note the RR for EPRT after ERT-only was 1.5, but the RR for EPRT-only was 1.1.