Tibolone—a synthetic steroid used to treat menopausal symptoms and to prevent osteoporosis—significantly increases the risk of recurrence for breast cancer patients, according to findings published Online First and in the February issue of The Lancet Oncology.
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 cancer presently use the drug to counteract the effects of the menopause.
Professor Peter Kenemans (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: tamoxifen might not be as widespread, for example, or patients might not be undergoing adjuvant systemic therapy.
"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", Prof Kenemans concludes. According to the authors, as things stand, 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.
Prof Peter Kenemans, Department of Obstetrics and Gynaecology, VU University Medical Centre, PO Box 7057, 1007 MB Amsterdam, Netherlands T) Telephone: +31 20 4444 813 E): kenemans@vumc.nl
For full Article see: http://press.thelancet.com/TLOtibolone.pdf
Notes to editors:
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 a multinational, multicentre, randomised, double-blind, parallel group, placebo-controlled trial, designed to assess the safety and efficacy of tibolone in women with vasomotor symptoms and a history of breast cancer.
The number of distant recurrences was significantly increased in the intervention group compared with placebo (37.8% increase).
Journal
The Lancet Oncology