Browsing Bergen Open Research Archive by Author "Helland, Thomas"
Now showing items 1-9 of 9
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The Active Tamoxifen Metabolite Endoxifen (4OHNDtam) Strongly Down-Regulates Cytokeratin 6 (CK6) in MCF-7 Breast Cancer Cells
Helland, Thomas; Gjerde, Jennifer; Dankel, Simon N; Fenne, Ingvild Sveinsgjerd; Skartveit, Linn; Drangevåg, Andreas; Bozickovic, Olivera; Flågeng, Marianne Hauglid; Søiland, Håvard; Mellgren, Gunnar; Lien, Ernst Asbjørn (Peer reviewed; Journal article, 2015-04-13)Introduction: Tamoxifen is an anti-estrogen drug used in treatment of Estrogen Receptor (ER) positive breast cancer. Effects and side effects of tamoxifen is the sumof tamoxifen and all itsmetabolites. 4-Hydroxytamoxifen ... -
Association of CYP2D6 genotype and tamoxifen metabolites with breast cancer recurrence in a low-dose trial
DeCensi, Andrea; Johansson, Harriet; Helland, Thomas; Puntoni, Matteo; Macis, Debora; Aristarco, Valentina; Caviglia, Silvia; Webber, Tania Buttiron; Briata, Irene Maria; D’Amico, Mauro; Serrano, Davide; Guerrieri-Gonzaga, Aliana; Bifulco, Ersilia; Hustad, Simon Steinar; Søiland, Håvard; Boni, Luca; Bonanni, Bernardo; Mellgren, Gunnar (Journal article; Peer reviewed, 2021)Low-dose tamoxifen halves recurrence in non-invasive breast cancer without significant adverse events. Some adjuvant trials with tamoxifen 20 mg/day had shown an association between low endoxifen levels (9–16 nM) and ... -
Effect of genetic variability in 20 pharmacogenes on concentrations of tamoxifen and its metabolites
Chen, Yuanhuang; Marcath, Lauren A.; Eliassen, Finn Magnus; Lende, Tone Hoel; Soiland, Havard; Mellgren, Gunnar; Helland, Thomas; Hertz, Daniel Louis (Journal article; Peer reviewed, 2021)Background: Tamoxifen, as a treatment of estrogen receptor positive (ER+) breast cancer, is a weak anti-estrogen that requires metabolic activation to form metabolites with higher anti-estrogenic activity. Endoxifen is the ... -
Generating a Precision Endoxifen Prediction Algorithm to Advance Personalized Tamoxifen Treatment in Patients with Breast Cancer
Helland, Thomas; Alsomairy, Sarah; Lin, Chenchia; Søiland, Håvard; Mellgren, Gunnar; Hertz, Daniel Louis (Journal article; Peer reviewed, 2021)Tamoxifen is an endocrine treatment for hormone receptor positive breast cancer. The effectiveness of tamoxifen may be compromised in patients with metabolic resistance, who have insufficient metabolic generation of the ... -
Importance of endocrine treatment adherence and persistence in breast cancer survivorship: a systematic review
Eliassen, Finn; Blåfjelldal, Vibeke; Helland, Thomas; Hjorth, Cathrine Fonnesbech; Hølland, Kari; Lode, Lise; Bertelsen, Bjørn-Erik; Janssen, Emiel; Mellgren, Gunnar; Kvaløy, Jan Terje; Søiland, Håvard; Lende, Tone Hoel (Journal article; Peer reviewed, 2023)Purpose Adjuvant endocrine treatment is essential for treating luminal subtypes of breast cancer, which constitute 75% of all breast malignancies. However, the detrimental side effects of treatment make it difficult for ... -
Low Z-4OHtam concentrations are associated with adverse clinical outcome among early stage premenopausal breast cancer patients treated with adjuvant tamoxifen
Helland, Thomas; Naume, Bjørn; Hustad, Steinar; Bifulco, Ersilia; Kvaløy, Jan Terje; Sætersdal, Anna Barbro; Synnestvedt, Marit; Lende, Tone Hoel; Gilje, Bjørnar; Mjaaland, Ingvil; Weyde, Kjetil; Blix, Egil Støre; Wiedswang, Gro; Borgen, Elin; Hertz, Daniel Louis; Janssen, Emiel; Mellgren, Gunnar; Søiland, Håvard (Journal article; Peer reviewed, 2021)Low 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 ... -
Serum concentrations of active tamoxifen metabolites predict long-term survival in adjuvantly treated breast cancer patients
Helland, Thomas; Henne, Nina; Bifulco, Ersilia; Naume, Bjørn; Borgen, Elin; Kristensen, Vessela N.; Kvaløy, Jan Terje; Lash, Timothy L; Grenaker, Grethe Irene; van Schaik, RHN; Janssen, Emiel; Hustad, Simon Steinar; Lien, Ernst Asbjørn; Mellgren, Gunnar; Søiland, Håvard (Peer reviewed; Journal article, 2017-11-28)Background: Controversies exist as to whether the genetic polymorphisms of the enzymes responsible for the metabolism of tamoxifen can predict breast cancer outcome in patients using adjuvant tamoxifen. Direct measurement ... -
Simultaneous Quantification of Aromatase Inhibitors and Estrogens in Postmenopausal Breast Cancer Patients
Bertelsen, Bjørn-Erik; Viste, Kristin; Helland, Thomas; Hagland, Magnus; Søiland, Håvard; Geisler, Jürgen; Lende, Tone Hoel; Lønning, Per Eystein; Sagen, Jørn Vegard; Mellgren, Gunnar; Almås, Bjørg (Journal article; Peer reviewed, 2021)Context Currently there are no assays that can simultaneously quantify serum levels of the third-generation aromatase inhibitors (AIs): letrozole, anastrozole, and exemestane, and the ultra-low levels of estrogens in ... -
Tamoxifen in the treatment of luminal breast cancer. Implications of active metabolites on gene expression, side effects and clinical outcome
Helland, Thomas (Doctoral thesis, 2019-02-21)Estrogen is a driver for the development and progression of luminal breast cancer, and up to 80% of all breast cancers diagnosed belong to the luminal subtype. The estrogenic effect on breast tumors can be reduced by the ...