Abstract Background:Prior research on the association between thyroid disease, ovarian cancer and borderline ovarian tumors has been inconsistent. This nationwide cohort study investigated the risk of epithelial ovarian cancer and borderline ovarian tumors among 1,058,745 Danish women born between January 1, 1960, and December 31, 1997, and were followed until December 31, 2022, in relation to hypothyroidism and hyperthyroidism. Methods:Data on thyroid diagnoses, ovarian tumors, covariates, migration, and vital status were retrieved from Danish national registers. Hazard ratios (HRs) and 95% confidence intervals (CIs) for ovarian cancer and borderline ovarian tumors overall and for histological subtypes were estimated using adjusted Cox proportional hazard models. A landmark analysis assessed ovarian tumor risk at age 60 by thyroid disease status before age 40. Results:Over a median 18.4 years of follow-up, 49,015 women developed hypothyroidism, 26,950 hyperthyroidism, 905 ovarian cancer and 1,111 borderline ovarian tumors. No association was found between hypothyroidism and ovarian cancer (HR: 1.10, CI: 0.78–1.55) or borderline tumors (HR: 0.88, CI: 0.60–1.29). Hyperthyroidism was associated with increased rates of serous ovarian cancer (HR: 1.62, CI: 1.00–2.63) and borderline ovarian tumors (HR: 1.78, CI: 1.26–2.52), especially in postmenopausal and premenopausal women, respectively. However, absolute risk differences at age 60 were small and not statistically significant. Conclusions:Hyperthyroidism may increase the rate of epithelial ovarian tumors, though clinical significance remains unclear, warranting further research. Impact:These findings indicate that hyperthyroidism may modestly influence epithelial ovarian tumor risk, underscoring the need to clarify shared biological mechanisms between thyroid and ovarian function.
Jensen et al. (Fri,) studied this question.