647Use of menopausal hormone therapy before and after ovarian cancer diagnosis and ovarian cancer survival

Background Menopausal hormone therapy (MHT) use before ovarian cancer (OvCa) diagnosis has been suggested to improve survival but data on type, duration and use after treatment for OvCa are scarce. Methods We investigated MHT use and OvCa survival among participants with newly diagnosed OvCA in the Ovarian cancer Prognosis And Lifestyle (OPAL) Study. Analysis of pre-diagnosis use was restricted to 661 post-menopausal women and analysis of post-diagnosis use included 254 women aged ≤55-years. We used multivariable Cox proportional hazards regression to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association between MHT and OvCa-specific survival. We used propensity score-based approaches to account for potential bias due to confounding by indication. Results Approximately 14% of post-menopausal women were current/recent users of oestrogen-only (7%) or oestrogen-progestin/unknown MHT (E-P=7%) at the time of diagnosis. In the pre-diagnosis analysis, E-P use was associated with better survival (HR = 0.60, 95%CI=0.37-0.98; HR = 0.93, 95%CI=0.79-1.09 per 5-years/use). The association between oestrogen-only MHT and survival was weaker and non-significant (HR = 0.74, 95%CI=0.47-1.16). Among women ≤55-years at diagnosis, the HR was 0.91 (95%CI=0.50-1.67) for new use after diagnosis regardless of type; and 0.89 (95%CI 0.51-1.54) for any use post-diagnosis compared to never users. Propensity-score-based methods showed similar estimates. Conclusions Pre-diagnosis MHT use is associated with better ovarian cancer survival. Post-diagnosis MHT use might also improve survival for women younger than 55-years, even after accounting for bias due to confounding by indication. Key messages Menopausal hormone therapy may be considered to manage menopausal symptoms in women with ovarian cancer.