THURSDAY, Aug. 27 (HealthDay News) -- High-dose fulvestrant, an estrogen receptor antagonist, appears to be at least as effective as the aromatase inhibitor anastrozole as a first-line endocrine therapy in postmenopausal women with advanced hormone receptor-positive breast cancer, according to research published online Aug. 24 in the Journal of Clinical Oncology.

John F.R. Robertson, M.D., of the University of Nottingham in the United Kingdom, and colleagues analyzed data from 205 patients, most with metastatic disease. Patients were randomized to receive either fulvestrant or anastrozole. The primary efficacy end point was clinical benefit rate, defined as the proportion of patients with an objective response or stable disease for at least 24 weeks.

The researchers found that the clinical benefit rate was similar in the two groups, as was the objective response rate, which was defined as the proportion with a complete or partial response. Time to progression was significantly longer in the fulvestrant group, and median time to progression was estimated to be 60 percent longer in the fulvestrant group than the anastrozole group. Both treatments were considered well-tolerated.

"In summary, fulvestrant high-dose is at least as effective as anastrozole in terms of clinical benefit rate and objective response rate, is associated with significantly longer time to progression, and therefore may offer longer-lasting disease control in the first-line advanced breast cancer setting. The results are therefore encouraging. Nonetheless, these data should be interpreted in the context of the limited power provided by a phase II, open-label study," the authors conclude.

Several co-authors reported financial relationships, including employment, with AstraZeneca, which provided medical writing support.

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