This study will be published in the October 1 issue of The Lancet Oncology. According to the study, there was a 1.7 times increase in death rates due to all causes in this age-category women. It was specifically high for estrogen-related cancers and diseases of the brain and cardiovascular system.
These discoveries were made unexpectedly by Walter Rocca, MD, Mayo Clinic neurologist, epidemiologist and lead study investigator, while investigating associations between ovary removal and brain diseases like Parkinson's and dementia.
"These findings reopen the debate about preventive removal of the ovaries for younger women," says Bobbie Gostout, MD, Mayo Clinic gynecologic surgeon who is not a study author but consulted with Dr. Rocca. "We don't see a dramatic increase in risk for early death from any one condition, but Dr. Rocca's study did show some increase in risk of death from breast and uterine cancers, and neurologic and vascular conditions. Collectively, this information tells us that a procedure that previously looked advantageous in protecting women's health may actually have disadvantages. We need to be very thoughtful about ovariectomy, as it may put younger women at risk for an earlier death."
Dr. Rocca says, "If a woman under 45 has ovarian cancer or a benign disease in the ovaries that requires removal, however, compelling reason remains to remove the ovaries. Removal may also be considered in older women and in women with a very high risk of ovarian cancer. "
Dr. Gostout points out that these findings will change her surgical practice for women under 45.
"For me this changes the nature of the discussion," she says. "Women in whom we've discovered ovarian cancer or benign disease of the ovary will still be counseled to have it treated, including ovariectomy. We will use the findings from the Mayo Clinic study to guide the discussion on estrogen replacement therapy and will encourage most young women to take estrogen until age 50. But, for women with average risk for breast and ovarian cancer where we might have considered preventive ovariectomy, the discussion will have more of an emphasis on conserving the ovaries for protecting the health of the woman."
"Continuing preventive ovariectomies in average-risk younger women and emphasizing estrogen replacement therapy thereafter may not be an adequate solution to diminish the risk, however, as compliance is poor for taking estrogen replacement therapy, " says Dr. Gostout. Dr. Rocca adds, "The protective effect from endogenous estrogen -- estrogen coming naturally from one's own ovaries with daily and monthly cyclic variations -- may not be the same as the effect of estrogen replacement therapy. "
The following are the theories proposed by the investigators to explain their findings:
* Premature estrogen deficiency following the surgery increased the risk for various diseases that in turn reduced survival
* The surgery revealed an underlying pre-existing condition in these women that caused early death following surgery
* These women may have a genetic predisposition to uterine diseases or other symptoms that prompted hysterectomy, which then prompted preventive ovariectomy, while the same predisposition also increased the risk of cancer or other causes of death following the surgery
"The study findings also have general research implications for the role of estrogen, " according to Dr. Rocca.
"Our results confirm that estrogen is probably protective of the brain and cardiovascular system," he says. "They also further establish that the effects of estrogen are age-dependent: estrogen may be clearly useful and protective at younger ages, but it may become less important after menopause and then may have no effect or may be disadvantageous if given as treatment in later years."
Women, who had undergone unilateral or bilateral ovariectomy between 1950 and 1987, were observed by the investigators, while living in Olmsted County, Minn., home of Mayo Clinic. All of them underwent the surgery before menopause and for reasons other than cancer.
1,293 cases of unilateral ovariectomy, 1097 cases of bilateral ovariectomy and 2,390 women without ovariectomy were examined till their deaths or until the end of the study. This was done with interviews with the women or a relative, medical records and death certificates.
"A unique strength of this study was a 25- to 30-year median follow-up time. A total of 1,292 women died during the follow-up; 33 of them died after undergoing bilateral ovariectomy for cancer prevention before age 45. Only a long-term study such as this can reveal these changes in death rates, " says Dr. Rocca.
1.2 million ovariectomies are performed every year in the U.S. Nearly 20,000 new cases of ovarian cancer will occur in 2006 and about 15,000 women will die from the disease this year, according to the American Cancer Society.
The other study authors are Brandon Grossardt; Mariza de Andrade, Ph.D.; George Malkasian, MD; and Joseph Melton III, MD.