2022 Update on menopause

Benefits of avoiding BSO in women at average risk of ovarian cancer

Erickson Z, Rocca WA, Smith CY, et al. Time trends in unilateral and bilateral oophorectomy in a geographically defined American population. Obstet Gynecol. 2022;139:724-734. doi: 10.1097/ AOG.0000000000004728.

In 2005, gynecologist William Parker, MD, and colleagues used modeling methodology to assess the long-term risks and benefits of performing bilateral salpingo-oophorectomy (BSO) at the time of hysterectomy for benign disease in women at average risk for ovarian cancer.²³ They concluded that practicing ovarian conservation until age 65 increased women’s long-term survival. Among their findings were that women with BSO before age 55 had an 8.6% excess overall mortality by age 80, while those with oophorectomy before age 59 had 3.9% excess mortality. They noted a sustained, but decreasing, mortality benefit until the age of 75 and stated that at no age did their model suggest higher mortality in women who chose ovarian conservation. Parker and colleagues concluded that ovarian conservation until at least age 65 benefited long-term survival for women at average risk for ovarian cancer when undergoing hysterectomy for benign disease.²³

Certain risks decreased, others increased

A second report in 2009 by Parker and colleagues from the large prospective Nurses’ Health Study found that, while BSO at the time of hysterectomy for benign disease was associated with a decreased risk of breast and ovarian cancer, BSO was associated with an increased risk of all-cause mortality, fatal and nonfatal coronary heart disease, and lung cancer.²⁴ Similar to the findings of the 2005 report, the authors noted that in no analysis or age group was BSO associated with increased survival. They also noted that compared with those who underwent BSO before age 50 and used ET, women with no history of ET use had an approximately 2-fold elevated risk of new onset coronary heart disease (HR, 1.98; 95% CI, 1.18–3.32).²⁴

In 2007, Walter Rocca, MD, a Mayo Clinic neurologist with a particular interest in the epidemiology of dementia, and colleagues at the Mayo Clinic published results of a study that assessed a cohort of women who had undergone unilateral oophorectomy or BSO prior to the onset of menopause.²⁵ The risk of cognitive impairment or dementia was higher in these women compared with women who had intact ovaries (HR, 1.46; 95% CI, 1.13-1.90). Of note, this elevated risk was confined to those who underwent oophorectomy before 49 years of age and were not prescribed estrogen until age 50 or older.²⁵

In a subsequent publication, Rocca and colleagues pointed out that BSO prior to menopause not only is associated with higher rates of all-cause mortality and cognitive impairment but also with coronary heart disease, parkinsonism, osteoporosis, and other chronic conditions associated with aging, including metabolic, mental health, and arthritic disorders.²⁶

Oophorectomy trends tracked

Given these and other reports²⁷ that highlighted the health risks of premenopausal BSO in women at average risk for ovarian cancer, Rocca and colleagues recently assessed trends in the occurrence of unilateral oophorectomy or BSO versus ovarian conservation among all women residing in the Minnesota county (Olmsted) in which Mayo Clinic is located, and who underwent gynecologic surgery between 1950 and 2018.²⁸

The investigators limited their analysis to women who had undergone unilateral oophorectomy or BSO between ages 18 and 49 years (these women are assumed to have been premenopausal). The authors considered as indications for oophorectomy primary or metastatic ovarian cancer, risk-reducing BSO for women at elevated risk for ovarian cancer (for example, strong family history or known BRCA gene mutation), adnexal mass, endometriosis, torsion, and other benign gynecologic conditions that included pelvic pain, abscess, oophoritis, or ectopic pregnancy. When more than 1 indication for ovarian surgery was present, the authors used the most clinically important indication. Unilateral oophorectomy or BSO was considered not indicated if the surgery was performed during another primary procedure (usually hysterectomy) without indication, or if the surgeon referred to the ovarian surgery as elective.

Results. Among 5,154 women who had oophorectomies between 1950 and 2018, the proportion of these women who underwent unilateral oophorectomy and BSO was 40.6% and 59.4%, respectively.

For most years between 1950 and 1979, the incidence of unilateral oophorectomy was higher than BSO. However, from 1980 to 2004, the incidence of BSO increased more than 2-fold while the incidence of unilateral surgery declined. After 2005, however, both types of ovarian surgery declined. During the years 2005–2018, a marked decline in BSO occurred, with the reduced incidence in premenopausal BSO most notable among women undergoing hysterectomy or those without an indication for oophorectomy.

Historically, ObGyns were taught that the benefits of removing normal ovaries (to prevent ovarian cancer) in average-risk women at the time of hysterectomy outweighed the risks. We agree with the authors’ speculation that beginning with Parker’s 2005 publication,²³ ObGyns have become more conservative in performing unindicated BSO in women at average risk for ovarian cancer, now recognizing that the harms of this procedure often outweigh any benefits.²⁸

Women with BRCA1 and BRCA2 gene mutations are at elevated risk for ovarian, tubal, and breast malignancies. In this population, risk-reducing BSO dramatically lowers future risk of ovarian and tubal cancer.

Data addressing the effect of RRSO in BRCA1 and BRCA2 gene mutation carriers continue to be evaluated, with differences between the 2 mutations, but they suggest that the surgery reduces not only ovarian cancer and tubal cancer but also possibly breast cancer.²⁹

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