Every year, about 600,000 women in the United States undergo hysterectomy — mostly for noncancerous conditions, such as fibroids endometriosis. More than half will have both ovaries removed as well, in a procedure called bilateral oophorectomy, which is performed chiefly to reduce the risk for ovarian cancer.

Women at high risk for breast cancer may also undergo bilateral oophorectomy to eliminate the ovarian production of estrogen, which fuels the growth of most breast cancers. A study calls these routine oophorectomies into question. Its conclusion: While almost eliminating ovarian cancer risk and reducing breast cancer risk, ovary removal increases the likelihood of fatal and nonfatal heart disease, lung cancer and death from all causes.

These findings add to the growing body of evidence that ovarian hormones are important to a woman’s health as she ages and that oophorectomy should not be routinely recommended, particularly for women at no more than average risk for ovarian or breast cancer.

A group of researchers led by Dr. William H. Parker of the John Wayne Cancer Institute at St. John’s Health Center, Santa Monica, Calif., analyzed data on 29,380 women participating in the Nurses’ Health Study. All of the women had undergone hysterectomy for noncancerous conditions; more than half (16,345) had both ovaries removed, while the rest kept their ovaries. The investigators analyzed health changes over a 24-year period, focusing on chronic conditions, such as heart disease, stroke, hip fracture and various cancers. They also evaluated causes of death and calculated overall death rates for the two groups. Multiple risk factors and estrogen use were taken into account.

Compared with women who kept their ovaries, those who underwent bilateral oophorectomy had a 17 percent higher risk of developing heart disease and a 28 percent increased risk of dying from it; they also had a 26 percent greater likelihood of getting lung cancer and a 31 percent higher risk of dying from it (an unexpected finding that the authors can’t explain).

Among the women whose ovaries were removed before age 50 and who didn’t take supplemental estrogen, the increased risks of lung cancer and stroke were considerably greater — 109 percent and 85 percent, respectively. Not surprisingly, oophorectomy was associated with a nearly zero risk of developing or dying from ovarian cancer and a 25 percent reduced risk of developing breast cancer. Overall, the risk of death from any cause was higher by 12 percent in women who had oophorectomies. That meant one additional death in the 35 years after surgery for every nine oophorectomies performed. Results were published in the May 2009 issue of Obstetrics and Gynecology.

This study doesn’t prove that bilateral oophorectomy causes harm, but the results are consistent with other findings of links between ovary removal and elevated risks for various later-life ills and premature death.

If you’re at high risk for ovarian and breast cancer because of family history or a gene mutation, such as BRCA1 or BRCA2, the benefits of oophorectomy may outweigh the risks. But for women at average risk, oophorectomy could cause problems down the road. Certainly discuss the matter with your clinician, but unless there’s a clear benefit, there’s no reason to have your ovaries removed during hysterectomy.