ABSTRACT
OBJECTIVE: To assess the associations between depot medroxyprogesterone acetate (DMPA) and endometrial cancer. METHODS: This multicenter case-control study was conducted among tertiary hospitals in Thailand. Patients were women with endometrial cancer. Controls were women admitted for other conditions, matched for age within 5 years of the patients' age. The controls had to have no abnormal vaginal bleeding, history of hysterectomy, or cancers of the other organs. A standardized questionnaire was used to gather information. Conditional logistic regression was applied to calculate adjusted odds ratio (aORs) and 95% confidence intervals (CIs). RESULTS: During 2015 to 2021, 378 patients and 1134 controls were included. Ever use of DMPA was associated with a 70% decreased overall risk of endometrial cancer (aOR, 0.30 [95% CI, 0.21-0.42]). Endometrial cancer risk declined by 3% (aOR, 0.97 [95% CI, 0.96-0.98]) for every 3 months of DMPA use. The magnitude of the decline in endometrial cancer risk did not vary appreciably by cancer subtypes (aOR, 0.26 [95% CI, 0.17-0.41] and 0.38 [95% CI, 0.22-0.65] for low-grade and high-grade tumors, respectively). CONCLUSIONS: Depot medroxyprogesterone acetate use was inversely associated with endometrial cancer risk in a duration-dependent manner. This association was independent of cancer subtype.