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dc.contributor.authorHelland, Thomas
dc.contributor.authorNaume, Bjørn
dc.contributor.authorHustad, Steinar
dc.contributor.authorBifulco, Ersilia
dc.contributor.authorKvaløy, Jan Terje
dc.contributor.authorSætersdal, Anna Barbro
dc.contributor.authorSynnestvedt, Marit
dc.contributor.authorLende, Tone Hoel
dc.contributor.authorGilje, Bjørnar
dc.contributor.authorMjaaland, Ingvil
dc.contributor.authorWeyde, Kjetil
dc.contributor.authorBlix, Egil Støre
dc.contributor.authorWiedswang, Gro
dc.contributor.authorBorgen, Elin
dc.contributor.authorHertz, Daniel Louis
dc.contributor.authorJanssen, Emiel
dc.contributor.authorMellgren, Gunnar
dc.contributor.authorSøiland, Håvard
dc.identifier.citationHelland, T., Naume, B., Hustad, S., Bifulco, E., Kvaløy, J. T., Sætersdal, A. B., ... & Søiland, H. (2021). Low Z‐4OHtam concentrations are associated with adverse clinical outcome among early stage premenopausal breast cancer patients treated with adjuvant tamoxifen. Molecular Oncology, 15(4), 957-967.en_US
dc.description.abstractLow steady‐state levels of active tamoxifen metabolites have been associated with inferior treatment outcomes. In this retrospective analysis of 406 estrogen receptor‐positive breast cancer (BC) patients receiving adjuvant tamoxifen as initial treatment, we have associated our previously reported thresholds for the two active metabolites, Z‐endoxifen and Z‐4‐hydroxy‐tamoxifen (Z‐4OHtam), with treatment outcomes in an independent cohort of BC patients. Among all patients, metabolite levels did not affect survival. However, in the premenopausal subgroup receiving tamoxifen alone (n = 191) we confirmed an inferior BC ‐specific survival in patients with the previously described serum concentration threshold of Z‐4OHtam ≤ 3.26 nm (HR = 2.37, 95% CI = 1.02–5.48, P = 0.039). The ‘dose–response’ survival trend in patients categorized to ordinal concentration cut‐points of Z‐4OHtamoxifen (≤ 3.26, 3.27–8.13, > 8.13 nm) was also replicated (P‐trend log‐rank = 0.048). Z‐endoxifen was not associated with outcome. This is the first study to confirm the association between a published active tamoxifen metabolite threshold and BC outcome in an independent patient cohort. Premenopausal patients receiving 5‐year of tamoxifen alone may benefit from therapeutic drug monitoring to ensure tamoxifen effectiveness.en_US
dc.publisherFEBS Pressen_US
dc.rightsNavngivelse 4.0 Internasjonal*
dc.titleLow Z-4OHtam concentrations are associated with adverse clinical outcome among early stage premenopausal breast cancer patients treated with adjuvant tamoxifenen_US
dc.typePeer revieweden_US
dc.typeJournal articleen_US
dc.rights.holderThe authorsen_US
dc.subject.nsiVDP::Medisinske Fag: 700en_US
dc.source.journalMolecular Oncologyen_US

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Navngivelse 4.0 Internasjonal
Except where otherwise noted, this item's license is described as Navngivelse 4.0 Internasjonal