Am J Obstet Gynecol. 2021 Sep 23. pii: S0002-9378(21)01048-6. [Epub ahead of print]
BACKGROUND: Opportunistic bilateral salpingo-oophorectomy (BSO) is often offered to patients undergoing benign hysterectomy to prevent ovarian cancer, but the magnitude of risk reduction obtained with BSO in this population remains unclear, and must be weighed against potential risks of ovarian hormone deficiency.OBJECTIVE: To quantify the relative and absolute risk reduction in ovarian cancer incidence and death associated with BSO at the time of benign hysterectomy.
STUDY DESIGN: We performed a population-based cohort study of all adult women (>20 years) undergoing benign hysterectomy from 1996 to 2010 in Ontario, Canada. Patients with ovarian pathology, prior breast/gynecologic cancer, or evidence of genetic susceptibility to malignancy were excluded. Inverse probability of treatment weighted Fine & Gray subdistribution hazard models were used to quantify the effect of BSO on ovarian cancer incidence and death, while accounting for competing risks and adjusting for demographic characteristics, gynecologic conditions, and comorbidities. Analyses were performed in all women, and specifically in women of postmenopausal age (>50 years) at the time of hysterectomy.
RESULTS: We identified 195,282 patients (BSO 24%; ovarian conservation 76%) with median age 45 years (interquartile range [IQR] 40-51). Over median follow-up of 16 years (IQR 12-20), 548 patients developed ovarian cancer (0.3%) and 16,170 died (8.3%) from any cause. BSO was associated with decreased ovarian cancer incidence (HR 0.23, 95% CI 0.14-0.38, p<0.001) and decreased ovarian cancer death (HR 0.30, 95% 0.16-0.57, p<0.001). At 20 years follow-up, the weighted cumulative incidence of ovarian cancer was 0.08% and 0.46% with BSO and ovarian conservation respectively, yielding an absolute risk reduction [ARR] of 0.38% (95% CI 0.32-0.45; number needed to treat [NNT] 260). After restricting to women aged >50 years at hysterectomy, the ARR was 0.62% (95% CI 0.47-0.77; NNT 161).
CONCLUSION: BSO results in a significant absolute reduction in ovarian cancer among women undergoing benign hysterectomy. Population-average risk estimates derived in this study should be balanced against other potential implications of BSO in order to inform practice guidelines, patient decision-making, and surgical management.
Keywords: Ovariectomy; gynecologic surgical procedures; hysterectomy; ovarian cancer