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Cited by 109Estrogen and related hormone effectsBreast Cancer Treatment StudiesAdvanced Breast Cancer Therapies

Letrozole: A Review of its Use in Postmenopausal Women with Advanced Breast Cancer

Lamb, Harriet M., Adkins, Julie C.·1998·Drugs
DOI 10.2165/00003495-199856060-00020
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Abstract

Unlabelled Letrozole is an oral reversible nonsteroidal aromatase inhibitor. Clinical tracer studies show that it inhibits peripheral aromatase by over 98% and suppresses blood and urinary estrogen levels by over 95% after 2 weeks of treatment in postmenopausal women. Letrozole also significantly inhibits intratumoral aromatase in vivo. The action of letrozole appears to be selective for aromatase; long term administration did not affect basal levels of 17 alpha-hydroxyprogesterone or aldosterone, although slight decreases in cortisol levels were observed in 2 studies, these did not appear to be clinically significant. In 2 phase IIb/III trials, letrozole 2.5 mg/day achieved objective response rates of 19.5 and 23.6% which were sustained for a median duration of 24 and 33 months, respectively. The median duration of response compared favourably with both comparator agents, aminoglutethimide and megestrol (15 and 18 months, respectively), as did objective response rates (12.4 and 16.4%). Letrozole 2.5 mg/day was associated with an increase in median survival time of 8 and 3 months compared with aminoglutethimide and megestrol, respectively. According to analyses of overall function, letrozole 2.5 mg/day was significantly superior to both comparators with respect to duration of response and aminoglutethimide with respect to survival. Letrozole has a good short term tolerability profile. The adverse events reported most commonly in association with letrozole 2.5 mg/day in the 2 phase IIb/III trials were headache (1.1 and 7%), nausea (6 and 10.3%), fatigue (3.2 and 5%), hot flushes (4.9 and 5%) and peripheral oedema (6%). Events were usually mild to moderate in severity; adverse events necessitated discontinuation of treatment in 3% of letrozole 2.5 mg/day recipients.Conclusions Letrozole, in common with vorozole and anastrozole, offers greater selectivity and potency of aromatase inhibition than the prototype aromatase inhibitor, aminoglutethimide, and can be administered once daily. Available clinical data suggest that letrozole achieves a significantly longer duration of response than megestrol and aminoglutethimide and longer overall survival than aminoglutethimide. However, direct comparisons are required to distinguish between the newer aromatase inhibitors. For this reason, letrozole should be recommended as a second-line treatment in postmenopausal women with advanced breast cancer whose disease has progressed on or failed to respond to antiestrogen therapy.

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Authors
Lamb, H. M., & Adkins, J. C.
Venue
Drugs
Publisher
Springer Science and Business Media LLC
Published
1998
Volume
56
Issue
6
Pages
1125-1140
ISSN
0012-6667 (ISSN-L)
DOI
10.2165/00003495-199856060-00020
OpenAlex
W3192809827
Cited by
109
References
42
Citations by year
2026: 1 · 2025: 5 · 2024: 8 · 2023: 4 · 2022: 11 · 2021: 5 · 2020: 7 · 2019: 5 · 2018: 1 · 2017: 4 · 2016: 1 · 2015: 2 · 2014: 2 · 2013: 1 · 2012: 5
FWCI
0.76
Type
journal article
Language
en
Open access
closed
Locations
Drugs (publishedVersion)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Estrogen and related hormone effects
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cancer Research › Breast Cancer Treatment Studies
  • Health Sciences › Medicine › Pulmonary and Respiratory Medicine › Advanced Breast Cancer Therapies
Keywords
letrozole, aromatase inhibitors, breast cancer, postmenopausal women, estrogen suppression, aminoglutethimide, megestrol, duration of response, survival, tolerability, adverse events, hot flashes, peripheral edema, anastrozole, vorozole, 17-hydroxyprogesterone, aldosterone, cortisol

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