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Contemporary evidence mandates contemporary guidelines: opportunistic oophorectomy at non‐malignant hysterectomy

Whether to perform opportunistic bilateral salpingooophorectomy (BSO) at the time of hysterectomy for nonmalignant indications remains one of the most contentious decisions in gynaecology. Proponents of BSO emphasise the importance of cancer prevention. Ovarian cancer has no effective modality for screening, is frequently diagnosed at an advanced stage and almost universally recurs after firstline treatment with limited prospects for cure. Proponents of ovarian conservation emphasise the importance of ovarian endocrine function. In premenopausal women, loss of estrogen disrupts many physiological processes1,2 and appears to have a negative influence on longterm morbidity and mortality. Ovarian conservation has therefore become the standard of care in this population.3 However, the risktobenefit ratio of opportunistic BSO may change as women age and ovarian estrogen production ceases with natural menopause. Could there be an age threshold after which BSO for ovarian cancer prevention might be safe? Two studies published in the early 2000s proposed that BSO at nonmalignant hysterectomy was associated with increased allcause mortality to at least age 65 years, and motivated many to conserve ovaries even after menopause.4,5 A Markov model by Parker et al.4 suggested that BSO was associated with significantly increased mortality when performed prior to age 65 years, and nonsignificantly increased mortality when performed prior to age 75 years. Decision analyses are only as robust as the data that inform them, and this model has since been critiqued for using estimates derived from studies with different target populations and exposure groups, and for potentially overestimating cardiovascular risk.6 A retrospective analysis of the Nurses’ Health Study by the same authors showed that BSO was associated with increased mortality (hazard ratio [HR] 1.13, 95% confidence interval [CI] 1.06– 1.21) and that this finding did not vary with age: an interaction between BSO status and age group (<50, 50– 59, ≥60 years) was not significant (P = 0.46). They concluded that opportunistic BSO at any age was not supported by their data.5 These findings were not replicated in a large body of evidence published over the subsequent decade. Observational studies have consistently shown that BSO is associated with increased allcause mortality when performed in women <45 or 50 years,7– 12 but not in women >50 years.7,8,11– 13 The most contemporary study to date was published by our group12 and uniquely used restricted cubic splines to depict the relation between BSO and allcause mortality as women aged; this approach allowed for greater flexibility in modelling age as a continuous variable, in whatever shape best described the data. We showed that BSO is associated with increased allcause mortality before age 50 years (<45 years: HR 1.31, 95% CI 1.18– 1.45; 45– 49 years: HR 1.16, 95% CI 1.04– 1.30) but that this risk gradually declines as women approach the average age of menopause and appears to be null thereafter (50– 54 years: HR 0.83, 95% CI 0.72– 0.97; ≥55 years: 0.92, 95% CI 0.82– 1.03). Use of hormone therapy could not be measured; as prescription and maintenance of hormone therapy varies between patients and providers after BSO, these results represent the realworld populationaverage association of BSO with mortality. Rush et al. recently published a revised Markov model with estimates from other observational studies that specifically compared BSO with ovarian conservation at the time of nonmalignant hysterectomy, and suggested that the age at which BSO could be safely performed without undue increased mortality was 50 years or older. The clear benefit of BSO is that it is associated with significantly decreased ovarian cancer incidence and mortality at any age;14 because ovarian cancer is rare, this benefit is unlikely to be reflected in estimates of allcause mortality. It is time for our speciality societies to update practice guidelines based on these contemporary data. The American College of Obstetrics & Gynecology (ACOG) published a practice bulletin on this topic in 2008 that was later retracted and never replaced.15 The Society of Obstetrics & Accepted: 7 October 2022 | Published Online 28 October 2022