Tibolone reduces fracture and breast cancer risk

Tibolone reduces the risk of fracture, breast cancer and possibly colon cancer among older women with osteoporosis, researchers have found. However, it was associated with an increased risk of stroke and should, therefore, not be used in elderly women or women with risk factors for stroke, (New England Journal of Medicine 2008;359:697).

In the study, 4,538 postmenopausal women, aged between 60 and 85 years who had a bone mineral density T score of –2.5 or less at the hip or spine or a T score of –2.0 or less and radiological evidence of a vertebral fracture, were randomly assigned to receive tibolone 1.25mg once daily or placebo. Annual spine radiographs were used to assess for vertebral fracture.

The researchers found that during a median of 34 months’ treatment, patients in the tibolone group, compared with the placebo group, had a decreased risk of vertebral fracture (70 cases versus 126 cases per 1,000 person-years) and non-vertebral fracture (122 cases versus 166 cases per 1,000 person-years).

In each group, the absolute reduction was greater among those who already had a vertebral or non-vertebral fracture, respectively. In addition, women in the tibolone group had a lower incidence of invasive breast cancer (relative hazard 0.32) and colon cancer (relative hazard 0.31).

The researchers also report that there were no significant differences in the risk of either coronary heart disease or venous thromboembolism between the two groups. However, tibolone was shown to double the risk of stroke, a risk that was greater in the first year of treatment and in women over 70 years of age.