High-dose fulvestrant helpful against breast cancer

NEW YORK (Reuters Health) - For first-line endocrine therapy in advanced hormone receptor-positive breast cancer in postmenopausal women, double the approved dose of fulvestrant does at least as well as anastrozole, researchers report in the August 24th issue of the Journal of Clinical Oncology.

The study, lead investigator Dr. John F. R. Robertson told Reuters Health, "suggests that a higher dose of fulvestrant -- 500 mg -- is more effective than a third generation aromatase inhibitor, although I think the data are not yet sufficient to change clinical practice."

Dr. Robertson of the University of Nottingham, UK, and colleagues came to this conclusion after an open-label study of 205 patients who were randomized to treatment with the pure antiestrogen fulvestrant or anastrozole. Those in the fulvestrant group were given 500 mg on day 14 of the first month and 500 mg per month thereafter. Anastrozole patients received 1 mg per day.

The proportion of patients experiencing an objective response or stable disease for at least 24 weeks was 72.5% in the fulvestrant group and 67.0% in the anastrozole group. The corresponding objective response rates were 36.0% and 35.5%. The duration of these responses also favored fulvestrant.

The time to progression was significantly greater for fulvestrant than anastrozole. In fact, the median time to progression was not reached for fulvestrant but was 12.5 months for anastrozole. Both treatments were well tolerated.

"Combined with other data," concluded Dr. Robertson, "it now appears that fulvestrant 500 mg is more effective than the current 250 mg dose, with no apparent difference in tolerability. Other studies to be reported later this year should provide a definitive answer on the clinical value of fulvestrant 500 mg."

J Clin Oncol 2009;27.

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