ArticleEndocrine connections2023
A method to detect fulvestrant interference in estradiol in breast cancer patients.
Article in Endocrine connections, 2023. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
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Who cites it
1 citing paper in PubMed, 2 citations in OpenAlex.
- Ovarian Escape in Hormone Receptor-Positive Breast Cancer: Mechanisms, Risk Factors, Clinical Consequences, and Management Strategies.Breast cancer (Dove Medical Press) · 2026Review
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Authors and funding
3 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Background: Fulvestrant resembles estradiol in its structure. Reports have been published concerning fulvestrant measured as estradiol by the immunoassays. This may induce falsely elevated estradiol results and wrongly impact medical decisions. Our aim was to confirm the interference of fulvestrant on estradiol concentration and test a method to identify the false results. Methods: Four serum samples with low estradiol levels were spiked with fulvestrant at various concentrations. Estradiol was then measured directly on serum (Dir), after a 1:5 dilution (Dil), and a ratio Dil/Dir was estimated. On the second part of the study, estradiol results (Dir, Dil and ratio Dil/Dir) from 14 women treated with fulvestrant were analysed, as well as from 14 patients not under this treatment. Results: The addition of exogenous fulvestrant to the serum samples induced a gradual rise on estradiol concentration with a mean ratio for the Dil/Dir samples of 2.1 ± 0.4 (range 1.7-2.9). Patients on fulvestrant treatment experienced a mean ratio for the Dil/Dir estradiol sample of 2.4 ± 0.4 (range 1.6-3.0). In the control group, a mean estradiol ratio Dil/Dir of 1.1 ± 0.1 was observed (range 0.8-1.3). No correlation between the number of days after fulvestrant injection and estradiol result (r = 0.531) was observed. Conclusion: Our study confirmed the interference of fulvestrant in the estradiol measurement by immunoassay. When fulvestrant was present, the estradiol ratio for Dil/Dir sample was about 2. In the control group, the ratio was around 1. The estradiol Dil/Dir ratio is a simple tool which can be used to identify fulvestrant false immunoassay estradiol results.
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