ArticleCancer chemotherapy and pharmacology2020
Exposure-response analysis of endoxifen serum concentrations in early-breast cancer.
Article in Cancer chemotherapy and pharmacology, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 11 papers.
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Who cites it
11 citing papers in PubMed, 15 citations in OpenAlex.
- Influence of endoxifen on mammographic density: results from the KARISMA-Tam trial.Journal of the National Cancer Institute · 2025Trial
- Therapeutic Drug Monitoring-Guided Adjuvant Tamoxifen Dosing in Patients with Early Breast Cancer: A Cost-Effectiveness Analysis from the Prospective TOTAM Trial.Clinical drug investigation · 2022Trial
- Assessing plastic waste associated with LC-MS/MS method validation procedures.Cancer chemotherapy and pharmacology · 2025Article
- Impact of Complex Genetic and Drug-Drug Interactions on Tamoxifen Metabolism and Efficacy.Journal of personalized medicine · 2025Review
- Effects of tamoxifen on cognitive function in patients with primary breast cancer.British journal of cancer · 2025Article
- Endoxifen Concentration Is Associated with Recurrence-Free Survival in Hormone-Sensitive Breast Cancer Patients.Cancer research and treatment · 2025Article
- Tamoxifen pharmacokinetics and pharmacodynamics in older patients with non-metastatic breast cancer.Breast cancer research and treatment · 2023Article
- Impact of Irradiation on the Pharmacokinetics and Biotransformation of Tamoxifen.Frontiers in oncology · 2022Article
- Precision Dosing of Targeted Therapies Is Ready for Prime Time.Clinical cancer research : an official journal of the American Association for Cancer Research · 2021Article
- Generating a Precision Endoxifen Prediction Algorithm to Advance Personalized Tamoxifen Treatment in Patients with Breast Cancer.Journal of personalized medicine · 2021Review
- ClinicalCancers · 2021Review
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Authors and funding
8 authors at 4 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
purposeTamoxifen is part of endocrine therapy in breast cancer treatment. Studies have indicated the use of endoxifen concentrations, tamoxifen active metabolite, to guide tamoxifen efficacy. Three endoxifen thresholds have been suggested (5.9 ng/ml, 5.2 ng/ml and 3.3 ng/ml) for therapeutic drug monitoring (TDM). Our aim was to validate these thresholds and to examine endoxifen exposure with clinical outcome in early-breast cancer patients using tamoxifen.
methodsData from 667 patients from the CYPTAM study (NTR1509) were available. Patients were stratified (above or below), according to the endoxifen threshold values for tamoxifen efficacy and tested by Cox regression. Logistic regressions to estimate the probability of relapse and tamoxifen discontinuation were performed.
resultsNone of the thresholds showed a statistically significant difference in relapse-free survival: 5.2 ng/ml threshold: hazard ratio (HR): 2.545, 95% confidence interval (CI) 0.912-7.096, p value: 0.074; 3.3 ng/ml threshold: HR: 0.728; 95% CI 0.421-1.258, p value: 0.255. Logistic regression did not show a statistically significant association between the risk of relapse (odds ratio (OR): 0.971 (95% CI 0.923-1.021, p value: 0.248) and the risk for tamoxifen discontinuation (OR: 1.006 95% CI 0.961-1.053, p value: 0.798) with endoxifen concentrations.
conclusionOur findings do not confirm the endoxifen threshold values for TDM nor does it allow definition of a novel threshold. These findings indicate a limited value of TDM to guide tamoxifen efficacy.
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