The DOI matches its Crossref record; 37 of the 37 references it cites were found in a registry or an index.
Influence of Letrozole and Anastrozole on Total Body Aromatization and Plasma Estrogen Levels in Postmenopausal Breast Cancer Patients Evaluated in a Randomized, Cross-Over Study
Abstract
PURPOSE: To compare the effects of the two novel, potent, nonsteroidal aromatase inhibitors anastrozole and letrozole on total-body aromatization and plasma estrogen levels. PATIENTS AND METHODS: Twelve postmenopausal women with estrogen receptor–positive, metastatic breast cancer were treated with anastrozole 1 mg orally (PO) and letrozole 2.5 mg PO once daily, each given for a time interval of 6 weeks in a randomized sequence. Total-body aromatization was determined before treatment and at the end of each treatment period using a dual-label isotopic technique involving isolation of the metabolites with high-performance liquid chromatography. Plasma levels of estrone (E 1 ), estradiol (E 2 ), and estrone sulfate (E 1 S) were determined in samples obtained before each injection using highly sensitive radioimmunoassays. RESULTS: Pretreatment aromatase levels ranged from 1.68% to 4.27%. On-treatment levels of aromatase were detectable in 11 of 12 patients during treatment with anastrozole (mean percentage inhibition in the whole group, 97.3%) but in none of the 12 patients during treatment with letrozole (> 99.1% suppression in all patients; Wilcoxon, P = .0022, comparing the two drug regimens). Treatment with anastrozole suppressed plasma levels of E 1 , E 2 , and E 1 S by a mean of 81.0%, 84.9%, and 93.5%, respectrively, whereas treatment with letrozole caused a corresponding decrease of 84.3%, 87.8% and 98.0%, respectively. The suppression of E 1 and E 1 S was found to be significantly better during treatment with letrozole compared with anastrozole (P = .019 and .0037, respectively). CONCLUSION: This study revealed letrozole (2.5 mg once daily) to be a more potent suppressor of total-body aromatization and plasma estrogen levels compared with anastrozole (1 mg once daily) in postmenopausal women with metastatic breast cancer.
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“Estrogen excess in turn has been associated with premature closure of the epiphyses, gynecomastia and low gonadotropin and testosterone levels.”
From Aromatase inhibitors in men: effects and therapeutic options (2011) · cites this paper as [25]
In the citing paper
“Estrogen excess in turn has been associated with premature closure of the epiphyses, gynecomastia and low gonadotropin and testosterone levels.”
From Aromatase inhibitors in men: effects and therapeutic options (2011) · cites this paper as [25]
In the citing paper
“Aromatase inhibitors effectively delay epiphysial maturation in boys and improve testosterone levels in adult men”
From Aromatase inhibitors in men: effects and therapeutic options (2011) · cites this paper as [25]
In the citing paper
“Estrogen excess in turn has been associated with premature closure of the epiphyses, gynecomastia and low gonadotropin and testosterone levels.”
From Aromatase inhibitors in men: effects and therapeutic options (2011) · cites this paper as [25]
In the citing paper
“Estrogen excess in turn has been associated with premature closure of the epiphyses, gynecomastia and low gonadotropin and testosterone levels.”
From Aromatase inhibitors in men: effects and therapeutic options (2011) · cites this paper as [25]
In the citing paper
“This approach proved successful in rare conditions such as the aromatase-excess syndrome [25] and high estrogen levels due to Sertoli cell tumors in boys with Peutz-Jeghers syndrome [55].”
From Aromatase inhibitors in men: effects and therapeutic options (2011) · cites this paper as [25]
In the citing paper
“Estrogens are essential for epiphysial maturation in boys.”
From Aromatase inhibitors in men: effects and therapeutic options (2011) · cites this paper as [25]
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Metadata
- Authors
- Geisler, J., Haynes, B., Anker, G., Dowsett, M., & Lønning, P. E.
- Affiliations
- Haukeland University Hospital (NO)
- Venue
- Journal of Clinical Oncology
- Published
- 2002-02-01
- Volume
- 20
- Issue
- 3
- Pages
- 751-757
- ISSN
- 0732-183X (ISSN-L)
- 1527-7755
- OpenAlex
- W2145819414
- Cited by
- 604
- References
- 37
- Citations by year
- 2026: 8 · 2025: 3 · 2024: 8 · 2023: 15 · 2022: 10 · 2021: 11 · 2020: 14 · 2019: 14 · 2018: 12 · 2017: 18 · 2016: 25 · 2015: 23 · 2014: 26 · 2013: 22 · 2012: 16
- FWCI
- 25.01
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Journal of Clinical Oncology (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Endocrinology › Estrogen and related hormone effects
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Cancer Research › Breast Cancer Treatment Studies
- Health Sciences › Medicine › Oncology › Advanced Breast Cancer Therapies
- Keywords
- letrozole, anastrozole, aromatase inhibitors, aromatization, plasma estrogen, estrone, estradiol, estrone sulfate, metastatic breast cancer, postmenopausal women, estrogen receptor-positive breast cancer, aromatase inhibition
- MeSH terms
- Letrozole, Anastrozole, Aged, Antineoplastic Agents, Aromatase, Breast Neoplasms, Chromatography, High Pressure Liquid, Enzyme Inhibitors, Estradiol, Estrogens, Estrone, Female, Humans, Middle Aged, Nitriles, Radioimmunoassay, Triazoles, Postmenopause, Cross-Over Studies, Antineoplastic Agents, Hormonal, Aromatase Inhibitors
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