Cognitive function may suffer
Analysis of data from the Mayo Clinic Cohort Study of Oophorectomy and Aging found that bilateral oophorectomy before the onset of menopause increased the risk of parkinsonism, cognitive impairment or dementia, and anxiety or depression, particularly if estrogen was not replaced.6-8 These risks increased with younger age at oophorectomy.
The Women’s Health Initiative found an increased risk of dementia or mild cognitive impairment in women who were treated by estrogen alone or estrogen plus progestin after age 65.41-44
These disparate conclusions suggest that estrogen may have a protective effect on the brain if it is given right after natural menopause or premenopausal oophorectomy, but deleterious effects if it is started years later.45
Other studies of endogenous estrogen and cognitive function are few and yield inconsistent results.
Ovarian conservation boosts long-term survival
When there is no family history of ovarian cancer, ovarian conservation appears to maximize survival among healthy women 40 to 65 years old who undergo hysterectomy for benign disease.46 Among healthy women hysterectomized before the age of 55, calculations suggest that 8.6% more would be alive at age 80 if their ovaries were conserved than if they were removed.46
A study from the Mayo Clinic found that all-cause mortality was significantly higher among women who underwent prophylactic bilateral oophorectomy before the age of 45 than it was among women in the control group (HR, 1.67; 95% CI, 1.16–2.40); it was particularly high in women who did not receive estrogen treatment before age 45 (HR, 1.93; 95% CI, 1.25–2.96).22
In a recent study, investigators used the Nurses’ Health Study database to explore the long-term health outcomes of 29,380 women who underwent hysterectomy.4 Of these women, 13,035 (44.4%) had their ovaries conserved, and 16,345 (55.6%) underwent bilateral oophorectomy. Follow-up was 24 years. Oophorectomy was associated with an increased risk of nonfatal CAD among all women (HR, 1.17; 95% CI, 1.02, 1.35), especially those who underwent the procedure before age 45 (HR, 1.26; 95% CI, 1.04, 1.54). Oophorectomy was associated with a markedly reduced risk of ovarian cancer but an increased risk of lung cancer (HR, 1.26; 95% CI, 1.02–1.56).
In regard to fatal events, oophorectomy increased the risk of death from all causes (HR, 1.12; 95% CI, 1.03, 1.21). Specifically, there was an increased risk of death from CAD (HR, 1.28; 95% CI, 1.00, 1.64), lung cancer (HR, 1.31; 95% CI, 1.02, 1.68), and all cancers (HR, 1.17; 95% CI, 1.04, 1.32). There was no overall difference in the risk of death from stroke, breast cancer, and colorectal cancer between women who underwent oophorectomy and those who retained their ovaries.
During the 24 years of follow-up, 37 women died from ovarian cancer, accounting for 1.2% of all deaths. At no age did oophorectomy show a survival benefit.
How this evidence should inform your practice
It is unfortunate that the entire body of evidence on the risks and benefits of bilateral salpingo-oophorectomy consists of observational studies, which have significant inherent limitations. Although the Nurses’ Health Study was the largest prospective study to examine the effect of oophorectomy on women’s health, and involved the longest follow-up, the study was observational, and oophorectomy and ovarian conservation were self-selected. Nevertheless, recent data suggest that a more detailed informed-consent process is warranted than the process in place. Informed consent should cover the risks and benefits of both oophorectomy and ovarian conservation.
Prophylactic oophorectomy is recommended only if a preponderance of the evidence establishes that it clearly benefits the patient. The studies described in this article suggest that bilateral oophorectomy does harm more often than it does good. Therefore, a cautious approach to oophorectomy at the time of hysterectomy is advised.
CASE RESOLVED
After you describe the risks and benefits of oophorectomy, and address the patient’s concerns about her family history of heart disease, she decides to keep her ovaries.