Ovarian cancer rates in the U.S. began to decline faster in 2002 around the time many older women went off hormone replacement therapy, according to a new study.
That year, the Women's Health Initiative (WHI) found that estrogen or estrogen plus progestin hormone therapy, prescribed for the symptoms of menopause, was linked to an increased risk of breast cancer, stroke and heart attack.
In a new analysis using census data, researchers found that ovarian cancer rates were falling by about one percent each year before 2002, then dropped by more than two percent per year.
The findings don't mean there's a cause-effect relationship between ovarian cancer and the hormone treatments, lead author Hannah Yang of the National Cancer Institute in Bethesda, Maryland, told Reuters Health by email. But the association is compelling, she said.
"Understanding exposures, such as (hormone therapy), within at-risk populations is useful for overall cancer prevention and control strategies, particularly for tumors that are difficult to treat, such as ovarian cancer," Yang said.
There were more than 22,000 cases of ovarian cancer diagnosed in 2012, with 15,500 deaths, Yang said.
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