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Letrozole

In Postmenopausal Hormone-Responsive Early-Stage Breast Cancer

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Abstract

▴ Letrozole is a highly selective, nonsteroidal, third-generation aromatase inhibitor approved for first-line and extended adjuvant therapy in postmenopausal women with hormone-responsive, early-stage breast cancer. Binding of letrozole to the haeme component of the cytochrome P450 subunit of aromatase inhibits estrogen biosynthesis throughout the body.

▴ As first-line adjuvant therapy in ≈8000 postmenopausal women with hormone-responsive, early-stage breast cancer, once-daily letrozole 2.5mg significantly prolonged disease-free survival (DFS; primary endpoint) and reduced the risk of relapse at distant sites relative to once-daily tamoxifen 20mg in the ongoing Breast International Group 1–98, double-blind, multinational trial. The median duration of follow-up for this primary core analysis was 25.8 months.

▴ Extended adjuvant therapy with once-daily letrozole 2.5mg significantly prolonged DFS relative to placebo treatment at a median follow-up of 30 months (primary endpoint) in the MA-17 trial in ≈5000 postmenopausal women who were disease free after 4.5–6 years of tamoxifen therapy for hormone-responsive, early-stage breast cancer.

▴ Letrozole treatment for up to 5 years was generally well tolerated in this clinical setting. As first-line treatment, relative to tamoxifen, letrozole was associated with a significantly lower incidence of venous thromboembolitic events, vaginal bleeding, hot flushes and night sweating, whereas the incidence of cardiac failure, bone fractures and arthralgia was higher in letrozole recipients.

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Notes

  1. The use of trade names is for product identification purposes only and does not imply endorsement.

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  1. Adis International Limited, 41 Centorian Drive, Private Bag 65901, Mairangi Bay, Auckland, 1311, New Zealand

    Lesley J. Scott & Susan J. Keam

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  1. Lesley J. Scott
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  2. Susan J. Keam
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Correspondence to Lesley J. Scott.

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Scott, L.J., Keam, S.J. Letrozole. Drugs 66, 353–362 (2006). https://doi.org/10.2165/00003495-200666030-00010

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