The FDA has approved a new indication for letrozole (Femara, Novartis Pharmaceutical Corp, East Hanover, NJ) as a first-line treatment for postmenopausal women with hormone receptor–positive or unknown locally advanced or metastatic breast cancer. Letrozole, a highly selective nonsteroidal aromatase inhibitor, was previously approved for treatment of advanced breast cancer in postmenopausal women with disease progression following antiestrogen therapy.
The new approval was based on a randomized, double-blind, multinational trial that compared dosages of letrozole, 2.5 mg per day, with tamoxifen, 20 mg per day, in 907 postmenopausal patients with locally advanced (stage IIIB or regional recurrence not amenable to treatment with surgery or radiation) or metastatic breast cancer. The median time to progression was 9.4 months for letrozole and 6.0 months for tamoxifen. Objective response rate (complete plus partial) for letrozole was 30% vs 20% for tamoxifen. Median follow-up time was about 18 months.
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