, Volume 66, Issue 3, pp 353–362


In Postmenopausal Hormone-Responsive Early-Stage Breast Cancer
Adis Drug Profile

DOI: 10.2165/00003495-200666030-00010

Cite this article as:
Scott, L.J. & Keam, S.J. Drugs (2006) 66: 353. doi:10.2165/00003495-200666030-00010


▴ 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.

Copyright information

© Adis Data Information BV 2006

Authors and Affiliations

  1. 1.Adis International LimitedMairangi Bay, AucklandNew Zealand