By Rebecca H. Allen, MD, MPH, Editor
SYNOPSIS: In this retrospective cohort study of 195,282 women who underwent benign hysterectomy with or without bilateral salpingo-oophorectomy (BSO), the group who underwent BSO had a decreased ovarian cancer incidence (hazard ratio, 0.23; 95% confidence interval, 0.14-0.38) at 16 years of follow-up compared to those who retained their ovaries.
SOURCE: Cusimano MC, Ferguson SE, Moineddin R, et al. Ovarian cancer incidence and death in average-risk women undergoing bilateral salpingo-oophorectomy at benign hysterectomy. Am J Obstet Gynecol 2022;226:220.e1-220.e26.
The authors conducted this study to ascertain the risk reduction in ovarian cancer among women in the general population who were undergoing hysterectomy for benign reasons without ovarian pathology and opting for bilateral salpingo-oophorectomy (BSO). Current guidelines are unclear as to whether routine BSO should be offered to this population for ovarian cancer risk reduction, and at what age the benefits of cancer prevention outweigh the cardiovascular and other risks of early surgical menopause. This was a population-based retrospective cohort study using linked research databases that collect healthcare information on all residents of Ontario, Canada. The residents of Ontario have access to universal healthcare. Inclusion criteria included adult women who underwent hysterectomy for a benign indication by any surgical approach from Jan. 1, 1996, to Dec. 31, 2010.
This period was chosen deliberately to be before bilateral salpingectomy alone became predominant. Patients were excluded if they were non-Ontario residents ineligible for universal health coverage, were having emergency hysterectomies or for a malignant indication, have had a history of breast or gynecologic malignancy or a susceptibility to malignancy, and had evidence of ovarian pathology or cysts preoperatively. The primary exposure was BSO at the time of hysterectomy compared to women who had one or both ovaries conserved at the time of surgery. The primary outcome was ovarian cancer incidence and the secondary outcome was ovarian cancer deaths. Other data collected included age, rural or urban residence, date of surgery, income, ethnicity, immigration status, gynecologic conditions, surgical approach, medical comorbidities, previous ovarian surgery, and previous tubal ligation.
The authors evaluated 195,282 patients who underwent hysterectomy with BSO performed in 46,661 women (23.9%) and ovarian conservation in 148,621 women (76.1%). The median follow-up for ovarian cancer occurrence was 16 years (interquartile range [IQR], 12-20) and during that time 548 women (0.3%) were diagnosed with ovarian cancer at a median age of 59.6 years (IQR, 51.3-72.3). Propensity scoring was used to adjust for clinical differences between the two groups. BSO reduced the risk of ovarian cancer compared with conserving the ovaries by almost 80% (hazard ratio [HR], 0.23; 95% confidence interval [CI], 0.14-0.38). A total of 240 women died from ovarian cancer (0.1%), and BSO reduced the risk of ovarian cancer death (HR, 0.30; 95% CI, 0.16-0.57).
COMMENTARY
Arguments in favor of removing the ovaries at the time of hysterectomy traditionally have included decreased risk of breast and ovarian cancer in the future as well as a reduced risk of future surgery to remove the adnexa. However, we know now that surgical menopause is associated with increased mortality due to all causes, cardiovascular disease, decreased sexual and cognitive functioning, and osteoporosis.1 It turns out that the postmenopausal ovary continues to secrete androgens and plays an important role in overall health that cannot always be replaced by postoperative hormone therapy. There is marked variation among surgeons as to whether BSO is recommended to patients undergoing benign hysterectomy. A previous study found that this variance was most pronounced in the perimenopausal 45- to 54-year-old age group.2 This variability of practice is evidence of a level of uncertainty among clinicians about whether to conserve or remove ovaries, since there are no national guidelines to follow in this area.
The current study found that the effect of BSO among an average-risk population markedly decreased ovarian cancer incidence and death. Previous studies on this topic were limited by selection bias and smaller sample sizes. The strengths of this study were a large cohort with long-term follow-up, exclusion of women with ovarian pathology at baseline, and adjustment for baseline differences using a high-quality database that captured the entire Ontario population.
This ovarian cancer risk reduction estimate can aid with patient counseling. The authors were unable to ascertain the effect of bilateral salpingectomy alone on future ovarian cancer incidence, since there were not enough patients in that group. However, after 2010, when the tubal origin hypothesis of ovarian cancer was published, more patients started undergoing bilateral salpingectomy. The authors will follow that group and publish results in the future.
The decision whether to remove ovaries at the time of hysterectomy must involve the patient in a shared decision-making, informed consent process. An older decision model published in 2005 recommended that routine prophylactic oophorectomy should not be performed before age 65 years.3 However, a recent study has challenged this model with more modern data and concluded, “With updated data, revised statistical modeling, and Bayesian integration to account for HR uncertainties, our Markov model predicts that, at or after age 50 years, the increased risks associated with concurrent BSO with hysterectomy for benign indication are negated … For those younger than age 50 years, we should counsel that retaining ovaries leads to decreased mortality; though, if BSO is necessary, the increased mortality can be mitigated with estrogen therapy.”4 This is an important new paradigm and likely will be reflected in future clinical guidelines.
REFERENCES
- Adelman MR, Sharp HT. Ovarian conservation vs. removal at the time of benign hysterectomy. Am J Obstet Gynecol 2018;218:269-279.
- Cusimano MC, Moineddin R, Chiu M, et al. Practice variation in bilateral salpingo-oophorectomy at benign abdominal hysterectomy: A population-based study. Am J Obstet Gynecol 2021;224:585.e1-585.e30.
- Parker WH, Broder MS, Liu Z, et al. Ovarian conservation at the time of hysterectomy for benign disease. Obstet Gynecol 2005;106:219-226.
- Rush SK, Ma X, Newton MA, Rose SL. A revised Markov model evaluating oophorectomy at the time of hysterectomy for benign indication: Age 65 years revisited. Obstet Gynecol 2022; Apr 7. doi: 10.1097/AOG0000000000004732. [Online ahead of print].
