LAUSR

Prediagnostic use of menopausal hormone therapy (MHT) has been suggested to be associated with improved survival of epithelial ovarian cancer (EOC). We investigated the potential long‐term survival benefit of prediagnostic MHT use in women ≥50 years with nonlocalized EOC using the Extreme study including all women in Denmark registered with nonlocalized EOC during 2000 to 2014 (N = 3776). We obtained individual‐level information on prediagnostic use of systemic estrogen therapy (ET) and estrogen plus progestin therapy (EPT) from the National Prescription Registry and estimated absolute and relative 5‐ and 10‐year survival probabilities with 95% confidence intervals (CIs) using pseudo‐values, taking into account histology, comorbidity, income and residual disease. Among women not having used prediagnostic MHT, 5‐ and 10‐year absolute survival probabilities were 19% and 11%, respectively. Compared to MHT nonusers, prediagnostic systemic ET use for 3 to 4 years and ≥ 5 years was associated with 1.43 (95% CI: 1.01‐2.02) and 1.22 (95% CI: 0.96‐1.55) times higher 5‐year survival probabilities, respectively. Ten‐year survival probabilities were also increased but not statistically significantly. Among prediagnostic EPT users, increased 5‐year (1.14, 95% CI: 0.85‐1.53) and 10‐year (1.38, 95% CI: 0.91‐2.08) survival probabilities were observed after use for 3 to 4 years compared to MHT nonuse, whereas EPT use for ≥5 years was not associated with long‐term survival of nonlocalized EOC. Our findings may suggest a better long‐term survival of nonlocalized EOC in women having used long‐term prediagnostic ET. However, the statistical precision of our results did not allow firm conclusions and more studies are needed.