Dienogest and the breast

In a clinical pilot study, 21 women with endometriosis have been primarely treated with dienogest 2 × 10 mg daily p.o. for 24 weeks. Besides the effect on endometriosis the action of such high-dose progestogen treatment on the breast was evaluated by breast ultrasound prior to medication and at 24 weeks of medical treatment. In all women, a significant size reduction of the mammary gland (p < 0.023) and regression of mastopathic changes were observed. There was a non-significant reduction (p = 0.089) of the maximum diameter of the ducts. The portion of the fatty tissue increased slightly, but not significantly (p = 0.348).