A pilot study of hormone replacement therapy with tibolone in women with mastopathic breasts.

OBJECTIVE: Our purpose was to investigate the effect of tibolone in a prospective randomized, double-blind pilot study in postmenopausal women with clinically palpable mastopathic changes. METHODS: Twenty postmenopausal non-users of hormone replacement therapy undergoing mammography were randomly allocated to receive either 2.5 mg tibolone (Livial, Organon) or placebo (2 mg lactose). Mammographic density according to the Wolfe classification, severity of breast discomfort, parity, smoking habits, body weight and follicle-stimulating hormone (FSH) and estradiol (E(2)) levels were documented at baseline and after 6 months of treatment. RESULTS: There were no statistically significant differences between the two treatment groups in terms of parity, smoking, body weight and FSH and E(2) levels. At 6 months, four patients in the tibolone group showed reduced breast density, compared with one patient in the placebo group. Whereas no significant differences were found between the two treatment groups when the categories 'minimal reduction' and 'reduction' in mammographic density were combined, combination of the categories 'no change' and 'minimal reduction' showed a significant difference (P<0.036). Also, women in the tibolone group showed a statistically significant improvement in breast discomfort (P<0.019). CONCLUSION: This pilot study showed decreases in breast density as well as an attendant significant alleviation of breast discomfort in women with baseline mastopathic changes treated with tibolone for 6 months, which may be due to the inhibitory effect of tibolone on the enzymes involved in the biosynthesis of estradiol demonstrated in previous trials and should be further evaluated in long-term studies.