An article in The Lancet Oncology’s February issue reports that a breast cancer patient´s risk of recurrence increases considerably with the use of Tibolone, a synthetic steroid used in preventing osteoporosis and treating menopausal symptoms. As a result, breast cancer survivors and current patients should not be givenTibolone.

Early menopause is frequently a result of breast cancer treatments, such as chemotherapy. Hot flushes, night sweats, and bone loss are some of the symptoms that can be relieved with hormonal therapies. As these drugs are thought to trigger cancer recurrence, they should not be prescribed.

The use of Tibolone is approved in 55 countries for treating osteoporosis and it is licensed in 90 countries to reduce the effects of menopause. The drug is currently used by many breast cancer patients to reduce the symptoms of menopause.

Professor Peter Kenemans (VU University Medical Centre, Amsterdam, Netherlands) and his team, evaluated whether a 2•5 mg daily dose of tibolone in women surgically treated for breast cancer and suffering from menopausal symptoms raised the risk of a return of the disease. Of the 3,098 women who were assessed, 1,556 were in the Tibolone group, and 1,542 in the control group, with an average of 52.7 years of age at entry, and 2.7 years since surgery.

The results showed a 40% higher risk for Tibolone recipients – 15.2% (237) of them with recurrence of their cancer – compared to 10.7% (165) of the women receiving a placebo. The assessment was stopped 6 month early because of the evident increased risk. In addition, these recurrences (70%) involved deadly metastases.

The fact that there is no detailed study of the primary tumours, and that breast-cancer risks factors were not evaluated, limits this investigation. Upcoming studies may consider different groups of breast-cancer patients, as well as the extent of the use of tamoxifen, and whether patients are undergoing adjuvant systemic therapy.

Prof Kenemans concludes, “There are insufficient data to establish the safety of tibolone in women who have had breast cancer and do not require or have finished adjuvant therapy.” There were no subgroups of breast-cancer patients identified who could safely use Tibolone. Therefore, according to the authors, for all such patients, its use should be avoided or discontinued.

This research has shown that Tibolone is and should remain contraindicated for use in women with a history of breast cancer.

Professor Kenemans and colleagues conducted the study on behalf of the LIBERATE (Livial Intervention following Breast cancer: Efficacy, Recurrence, And Tolerability Endpoints) Study Group. LIBERATE was intended to evaluate the effectiveness and safety of tibolone in women with a history of breast cancer and vasomotor symptoms. The trial was multinational, multicentre, randomised, double-blind, parallel group and placebo-controlled.

The intervention group had a considerable number of distant recurrences (37.8% increase) in comparison to the placebo group.

The Lancet Oncology

Written by Stephanie Brunner (B.A.)