Clinical effects of tibolone in postmenopausal women after 5 years of tamoxifen therapy for breast cancer

Objectives This observational, prospective, open, non-randomized study was designed to assess the safety and efficacy of tibolone for the treatment of climacteric symptoms in women with a history of breast cancer. Methods A total of 156 women who had been treated for breast cancer and had received tamoxifen for 5 years participated in the study. One month after stopping tamoxifen, 52 women started taking tibolone while the rest served as untreated controls (n = 104). They were followed up (mean duration 61 months) for climacteric symptoms, cancer recurrence rate, breast density, endometrial thickness and adverse events. Results There was no difference in cancer recurrence rate between the two groups. Breast density was not affected. Tibolone treatment alleviated climacteric symptoms and positively affected sexual problems. Endometrial thickness was not adversely affected by treatment and there was a low incidence of adverse events. Conclusions Tibolone was effective in the treatment of climacteric symptoms and well tolerated in a group of 52 women with a history of breast cancer. The cancer recurrence rate in the tibolone group was comparable to that of untreated controls. It should be noted that the limitations of the study design and the small number of events preclude any definitive conclusions about the effects of tibolone on breast cancer recurrence in general clinical practice. There were no breast-related adverse effects, and overall safety and tolerance were similar to those of the general population of postmenopausal women treated with tibolone.