Background
Menopausal hormone therapy (MHT) use before ovarian cancer (OvCa) diagnosis has been associated with improved survival; however, data on use (type, duration) are scarce and there is limited evidence on MHT use after OvCa treatment and survival.
Methods
We investigated MHT use and OvCa survival among participants with newly diagnosed OvCa in the Ovarian cancer Prognosis And Lifestyle (OPAL) Study, a prospectively nationwide cohort study. Analysis of pre-diagnosis use included 661 post-menopausal women and analysis of post-diagnosis use was restricted to 282 women aged ≤55 years or who were older but continued using MHT after treatment. 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 (PS) 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. Ever use of MHT pre-diagnosis was associated with a non-significant 16% improvement in OvCa-specific survival (HR 0.84, 95%CI 0.68-1.05). The association with MHT appeared to be stronger among women with early-stage (1&2) disease (HR 0.46, 95%CI 0.16-1.30) than women with advanced disease (HR 0.76, 95%CI 0.61-0.95). After treatment for OvCa, the HR was 0.84 (95%CI=0.48-1.46) for new use; and 0.92 (95%CI 0.58-1.45) for any use post-treatment compared to never users. The association was slightly attenuated towards the null in time-varying and the PS analysis.
Conclusions
Pre-diagnosis MHT use may influence ovarian cancer survival. There was no clear evidence that MHT use after treatment for ovarian cancer is associated with survival, even after accounting for bias due to confounding by indication.