Effects of menopausal hormone therapy on the risk of ovarian cancer: Health Insurance Database in South Korea-based cohort study

ObjectiveThis study aimed to evaluate the risk of ovarian cancer associated with hormone therapy regimens using a Korean population-based study.MethodsThis retrospective cohort study used national health checkup and insurance data from January 1, 2002, to December 31, 2019, provided by Korea's National Health Insurance Service. Women older than 40 years who recorded "menopause" in the questionnaire from 2002 to 2011 were included in this study. Menopausal hormone therapy (MHT) preparations were classified into tibolone, combined estrogen plus progestin by the manufacturer, combined estrogen plus progestin by physician, estrogen, and topical estrogen groups. The number of participants recorded as menopausal during the national health examination between 2002 and 2011 was 2,506,271. The MHT and non-MHT groups consisted of 373,271 and 1,382,653 patients, respectively. The hazard ratios (HR) of ovarian cancer according to MHT type, age at inclusion, body mass index, region, socioeconomic status, Charlson comorbidity index, age at menarche, age at menopause, parity, smoking, alcohol consumption, physical exercise, and period from menopause to inclusion were evaluated.ResultsThe risk of ovarian cancer was reduced in the tibolone group (HR, 0.84; 95% confidence interval, 0.75-0.93; P = 0.003) and in patients in rural areas (HR, 0.90; 95% confidence interval, 0.845-0.98; P = 0.013). The risk of ovarian cancer was not related to the other MHT treatments.ConclusionTibolone was associated with a lower risk of ovarian cancer. No other MHT was associated with ovarian cancer.