Article
LIBERATE trial: A safety study of tibolone in breast cancer surgery patients - design and baseline data
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Published: | March 20, 2006 |
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Background/Objectives: Hormone therapy is contraindicated in women with a history of breast cancer (BC). A pilot study has shown that tibolone relieves vasomotor symptoms in patients receiving tamoxifen after BC surgery. Studies have also shown that tibolone does not stimulate breast tissue, prevents osteoporosis and might therefore be a promising agent to treat vasomotor symptoms in these women. LIBERATE was designed as a randomized, double-blind 5-year trial to evaluate that tibolone 2.5 mg/day (Livial®) is non-inferior to placebo regarding BC recurrence in women with vasomotor symptoms who have been surgically treated for primary BC within the last 5 years. Secondary objectives are overall survival as well as effects on vasomotor symptoms, BMD and health-related QoL.
Methods: Patients were eligible when they had histologically confirmed and surgically treated invasive BC (T1-3, N0-2, M0). In non-hysterectomized women, entry required normal thickness of endometrium as judged by ultrasound, defined as absence of endometrial polyps in tamoxifen users and double-layer thickness </=4 mm or 4-8 mm (when inactive/atrophic) in non-tamoxifen users. The primary end-point is BC recurrence, including contralateral. Yearly BMD will be assessed in a subset of patients. The primary analysis will be performed mid 2007, with a follow-up analysis on all data in 2009.
Baseline data: Recruitment started in July 2002 and was completed in December 2004. 3149 patients were randomized at 245 centers in 31 countries worldwide. Based on the data in May 2005, the mean age at randomization was 53 years, the mean body mass index 27, and the mean time since surgery 2.1 years. The mean daily number of hot flushes and sweating episodes was 7 and 6, respectively. A pathological tumor size of > 2.0 cm (T2/3) was originally reported for 48% of the patients and a node positive status (N1/2) for 58%. Of the 78% patients with a known receptor status, 79% were ER+, 66% were PR+, and 61% were both ER+ and PR+. 74% received tamoxifen and 9% aromatase inhibitors. Regular unblinded safety reviews performed so far by an independent DSMB have led to recommendations to continue without modification.
Discussion: Tibolone has been shown to relieve vasomotor symptoms after BC surgery. Several trials investigating the effects of E(P)T on BC risk were stopped prematurely. The LIBERATE trial remains the largest and only ongoing, well-controlled study in this field investigating breast safety.