Tibolone ( Livial ), a synthetic steroid used to treat menopausal symptoms and to prevent osteoporosis, significantly increases the risk of recurrence for breast cancer patients.
Tibolone should not, therefore, be prescribed to any woman with known, past, or suspected breast cancer.

Women with breast cancer undergoing treatments such as chemotherapy often find themselves subject to an early menopause. They face debilitating symptoms such as hot flushes, night sweats, and bone loss. Such episodes can be mitigated by hormonal therapies, but concerns that these drugs might cause a recurrence of the cancer have led to hormonal therapies being ruled out for patients with breast cancer.

Tibolone is licensed for use in 90 countries for alleviating the symptoms of the menopause; 55 countries have approved its use in treating osteoporosis. Many patients with breast tumor presently use the drug to counteract the effects of the menopause.

Peter Kenemans at VU University Medical Centre, Amsterdam, Netherlands, and colleagues assessed whether a dose of 2•5 mg per day of Tibolone increases the risk of breast-cancer recurrence in women experiencing hot flushes and associated complaints who have been surgically treated for breast cancer; 3098 women were assessed, 1556 in the tibolone group, and 1542 in the placebo. Mean age at entry was 52.7 years, mean time since surgery was 2.7 years.

237 ( 15.2% ) of the women receiving Tibolone had a recurrence of their cancer, compared with 165 ( 10.7% ) of the women receiving placebo, which was a 40% increased risk for the Tibolone recipients. The increased risk was so pronounced that the trial was stopped 6 months early. Moreover, 70% of these recurrences were distant metastases, which are invariably fatal.

There are limitations to the study, breast-cancer risk factors were not assessed, nor were the primary tumours subject to detailed analysis. The profile of future groups of breast-cancer patients might differ from that of the survey:Ttamoxifen might not be as widespread, for example, or patients might not be undergoing adjuvant systemic therapy.

According to Authors, 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. No subgroup of breast-cancer patients for which the use of Tibolone is safe can be identified and its use should be discontinued for all such patients.

Tibolone is contraindicated for use in women with a history of breast cancer, this study has shown that this contraindication should be maintained.

Source: Lancet Oncology, 2009

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