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dc.contributor.authorRitte, Rebecca
dc.contributor.authorTikk, Kaja
dc.contributor.authorLukanova, Annekatrin
dc.contributor.authorTjønneland, Anne
dc.contributor.authorOlsen, Anja
dc.contributor.authorOvervad, Kim
dc.contributor.authorDossus, Laure
dc.contributor.authorFournier, Agnes
dc.contributor.authorClavel-Chapelon, Françoise
dc.contributor.authorGrote, Verena
dc.contributor.authorBoeing, Heiner
dc.contributor.authorAleksandrova, Krasimira
dc.contributor.authorTrichopoulou, Antonia
dc.contributor.authorLagiou, Pagona
dc.contributor.authorTrichopoulos, Dimitrios
dc.contributor.authorPalli, Domenico
dc.contributor.authorBerrino, Franco
dc.contributor.authorMattiello, Amalia
dc.contributor.authorTumino, Rosario
dc.contributor.authorSacerdote, Carlotta
dc.contributor.authorQuirós, José Ramón
dc.contributor.authorBuckland, Genevieve
dc.contributor.authorMolina-Montes, Esther
dc.contributor.authorChirlaque, María Dolores
dc.contributor.authorArdanaz, Eva
dc.contributor.authorAmiano, Pilar
dc.contributor.authorBueno-de-Mesquita, H. Bas
dc.contributor.authorvan Gils, Carla H.
dc.contributor.authorPeeters, Petra H M
dc.contributor.authorWareham, Nick
dc.contributor.authorKhaw, Kay-Tee
dc.contributor.authorKey, Timothy J
dc.contributor.authorTravis, Ruth C.
dc.contributor.authorWeiderpass, Elisabete
dc.contributor.authorDumeaux, Vanessa
dc.contributor.authorLund, Eiliv
dc.contributor.authorSund, Malin
dc.contributor.authorAndersson, Anne
dc.contributor.authorRomieu, Isabelle
dc.contributor.authorRinaldi, Sabina
dc.contributor.authorVineis, Paolo
dc.contributor.authorMerritt, Melissa A
dc.contributor.authorRiboli, Elio
dc.contributor.authorKaaks, Rudolf
dc.date.accessioned2014-03-20T13:17:32Z
dc.date.available2014-03-20T13:17:32Z
dc.date.issued2013
dc.description.abstractBackground The association of reproductive factors with hormone receptor (HR)-negative breast tumors remains uncertain. Methods Within the EPIC cohort, Cox proportional hazards models were used to describe the relationships of reproductive factors (menarcheal age, time between menarche and first pregnancy, parity, number of children, age at first and last pregnancies, time since last full-term childbirth, breastfeeding, age at menopause, ever having an abortion and use of oral contraceptives [OC]) with risk of ER-PR- (n = 998) and ER+PR+ (n = 3,567) breast tumors. Results A later first full-term childbirth was associated with increased risk of ER+PR+ tumors but not with risk of ER-PR- tumors (≥35 vs. ≤19 years HR: 1.47 [95% CI 1.15-1.88] ptrend < 0.001 for ER+PR+ tumors; ≥35 vs. ≤19 years HR: 0.93 [95% CI 0.53-1.65] ptrend = 0.96 for ER-PR- tumors; Phet = 0.03). The risk associations of menarcheal age, and time period between menarche and first full-term childbirth with ER-PR-tumors were in the similar direction with risk of ER+PR+ tumors (phet = 0.50), although weaker in magnitude and statistically only borderline significant. Other parity related factors such as ever a full-term birth, number of births, age- and time since last birth were associated only with ER+PR+ malignancies, however no statistical heterogeneity between breast cancer subtypes was observed. Breastfeeding and OC use were generally not associated with breast cancer subtype risk. Conclusion Our study provides possible evidence that age at menarche, and time between menarche and first full-term childbirth may be associated with the etiology of both HR-negative and HR-positive malignancies, although the associations with HR-negative breast cancer were only borderline significant.en
dc.identifier.citationBMC Cancer 13:584(2013)en
dc.identifier.cristinIDFRIDAID 1091427
dc.identifier.doi10.1186/1471-2407-13-584
dc.identifier.issn1471-2407
dc.identifier.urihttps://hdl.handle.net/10037/5991
dc.identifier.urnURN:NBN:no-uit_munin_5682
dc.language.isoengen
dc.publisherBioMed Centralen
dc.rights.accessRightsopenAccess
dc.subjectVDP::Medical disciplines: 700::Clinical medical disciplines: 750::Oncology: 762en
dc.subjectVDP::Medisinske Fag: 700::Klinisk medisinske fag: 750::Onkologi: 762en
dc.titleReproductive factors and risk of hormone receptor positive and negative breast cancer: a cohort study.en
dc.typeJournal articleen
dc.typeTidsskriftartikkelen
dc.typePeer revieweden


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