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dc.contributor.authorFjeldheim, Frøydis Nyborg
dc.contributor.authorFrydenberg, Hanne
dc.contributor.authorFlote, Vidar Gordon
dc.contributor.authorMcTiernan, Anne
dc.contributor.authorFurberg, Anne-Sofie
dc.contributor.authorEllison, Peter T.
dc.contributor.authorBarrett, Emily S.
dc.contributor.authorWilsgaard, Tom
dc.contributor.authorJasienska, Grazyna
dc.contributor.authorUrsin, Giske
dc.contributor.authorWist, Erik
dc.contributor.authorThune, Inger
dc.date.accessioned2017-03-17T13:48:09Z
dc.date.available2017-03-17T13:48:09Z
dc.date.issued2016-10-07
dc.description.abstractBackground: Single nucleotide polymorphisms (SNPs) involved in the estrogen pathway and SNPs in the estrogen receptor alpha gene (ESR1 6q25) have been linked to breast cancer development, and mammographic density is an established breast cancer risk factor. Whether there is an association between daily estradiol levels, SNPs in ESR1 and premenopausal mammographic density phenotypes is unknown. Methods: We assessed estradiol in daily saliva samples throughout an entire menstrual cycle in 202 healthy premenopausal women in the Norwegian Energy Balance and Breast Cancer Aspects I study. DNA was genotyped using the Illumina Golden Gate platform. Mammograms were taken between days 7 and 12 of the menstrual cycle, and digitized mammographic density was assessed using a computer-assisted method (Madena). Multivariable regression models were used to study the association between SNPs in ESR1, premenopausal mammographic density phenotypes and daily cycling estradiol. Results: We observed inverse linear associations between the minor alleles of eight measured SNPs (rs3020364, rs2474148, rs12154178, rs2347867, rs6927072, rs2982712, rs3020407, rs9322335) and percent mammographic density (p-values: 0.002–0.026), these associations were strongest in lean women (BMI, ≤23.6 kg/m2.). The odds of abovemedian percent mammographic density (>28.5 %) among women with major homozygous genotypes were 3–6 times higher than those of women with minor homozygous genotypes in seven SNPs. Women with rs3020364 major homozygous genotype had an OR of 6.46 for above-median percent mammographic density (OR: 6.46; 95 % Confidence Interval 1.61, 25.94) when compared to women with the minor homozygous genotype. These associations were not observed in relation to absolute mammographic density. No associations between SNPs and daily cycling estradiol were observed. However, we suggest, based on results of borderline significance (p values: 0.025–0.079) that the level of 17β-estradiol for women with the minor genotype for rs3020364, rs24744148 and rs2982712 were lower throughout the cycle in women with low (<28.5 %) percent mammographic density and higher in women with high (>28.5 %) percent mammographic density, when compared to women with the major genotype.en_US
dc.description.sponsorshipThis work was supported by the University Hospital of Oslo; Foundation for the Norwegian Health and Rehabilitation Organization (grant number 59010–2000, 59010–2001, 59010–2002); and Norwegian Cancer Society (grant number 05087, TP 49 258). The funders did not influence the conduct of the study, the preparation of this paper, or the decision to publish.en_US
dc.descriptionPublished version. Source at http://doi.org/10.1186/s12885-016-2804-1. License CC BY 4.0.en_US
dc.identifier.citationFjeldheim FN, Frydenberg H, Flote VG, McTiernan A, Furberg AS, Ellison PT, Barrett ES, Wilsgaard T, Jasienska G, Ursin G, Wist E, Thune I. Polymorphisms in the estrogen receptor alpha gene (ESR1), daily cycling estrogen and mammographic density phenotypes. BMC Cancer. 2016;16:776:1-12en_US
dc.identifier.cristinIDFRIDAID 1403591
dc.identifier.doi10.1186/s12885-016-2804-1
dc.identifier.issn1471-2407
dc.identifier.urihttps://hdl.handle.net/10037/10771
dc.language.isoengen_US
dc.publisherBioMed Centralen_US
dc.relation.journalBMC Cancer
dc.rights.accessRightsopenAccessen_US
dc.subjectVDP::Medisinske Fag: 700::Klinisk medisinske fag: 750en_US
dc.subjectVDP::Medical disciplines: 700::Clinical medical disciplines: 750en_US
dc.subjectVDP::Medisinske Fag: 700::Helsefag: 800en_US
dc.subjectVDP::Medical disciplines: 700::Health sciences: 800en_US
dc.subjectPolymorphismsen_US
dc.subjectMammographic densityen_US
dc.subjectESR1en_US
dc.subject17β-estradiolen_US
dc.subjectPremenopausaen_US
dc.titlePolymorphisms in the estrogen receptor alpha gene (ESR1), daily cycling estrogen and mammographic density phenotypesen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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