Ovarian removal and subsequent breast cancer prognosis: a nationwide cohort study

Purpose To evaluate whether previous ovarian removal concomitant with benign hysterectomy improves prognosis in a cohort of women with breast cancer. Methods In this nationwide register-based cohort study, risk of recurrence and mortality were examined in 4563 women with invasive breast cancer and previous bilateral salpingo-oophorectomy (BSO) concomitant with benign hysterectomy, during 1977–2018. Comparing with benign hysterectomy alone, hazard ratios (HRs) and 95% confidence intervals (CIs) were evaluated by Cox-proportional hazards regression models. Analyses were stratified on age at hysterectomy as a proxy for menopausal status (< 45, 45–54 and ≥ 55 years); tumor characteristics, estrogen receptor (ER)-status, and use of hormone therapy (HT) were included in multivariable models. Results Compared with hysterectomy alone, premenopausal (< 45 years) BSO at benign hysterectomy was associated with an age and calendar period adjusted HR of 1.48 (95% CI 0.83–2.65) for breast cancer recurrence within 10 years of follow-up, a HR of 1.07 (95% CI 0.66–1.72) for overall mortality after breast cancer, and a HR of 0.59 (95% CI 0.26–1.32) for breast cancer-specific mortality. The corresponding HRs for postmenopausal (≥ 55 years) BSO at benign hysterectomy were 1.51 (95% CI 0.73–3.12) for recurrences, 1.34 (95% CI 0.74–2.44) for overall mortality, and 1.78 (95% CI 0.74–4.30) for breast cancer mortality. Adjusting for tumor characteristics, ER-status and HT did not alter the results. Conclusion Results from this cohort study did not indicate an improvement in breast cancer prognosis when removing the ovaries at benign hysterectomy prior to the cancer diagnosis.