The provocative study, being published Monday in the journal Obstetrics & Gynecology, does not settle the issue. It does not track actual patients, but uses other data to create a model of the surgery's effects.

Still, the work promises to raise questions from women and their doctors about a procedure long accepted despite little evidence to back it.

No Evidence

Some 615,000 hysterectomies -- the surgical removal of all or part of the uterus -- are performed every year. Ninety percent of them are for noncancerous reasons. More than half of those women also get their ovaries removed not because the ovaries are diseased but as a protective measure against developing ovarian cancer in the future.

Ovary removal, or oophorectomy, has been deemed protective for women at high risk of ovarian cancer because they harbor cancer-causing genes or have a family history of the disease.

There is no evidence about whether ovary removal benefits other women, who make up a majority of these surgeries, said Dr. William H. Parker of the University of California, Los Angeles.

Yet most gynecologists consider a protective oophorectomy standard for any women having her uterus removed after age 45, he said.

Abrupt Loss of Hormones

The thinking is that with childbearing over, menopause imminent, and ovarian cancer particularly deadly because there is no way to screen for it, it is best to catch it early. If the ovaries are removed, so is that concern.

But even after menopause, the ovaries do continue to produce a small amount of hormones, including testosterone that the body later converts into estrogen.

Parker wondered if the abrupt loss of all those hormones through ovary removal would outweigh most women's low risk of ovarian cancer.

He used data from other studies about women's mortality risks in general and some that tracked heart attacks and bone-thinning osteoporosis in oophorectomy patients. Parker created a model of how women with different characteristics would fare with ovary removal at different ages.

Ovary removal did not show a clear benefit for women of any age, Parker said. For women whose ovaries were removed before 65, the models suggest that oophorectomy actually increases the risk of dying from heart disease, he concluded.