title: Early pregnancy sex steroids and maternal breast cancer: a nested case-control study.
abstract: Pregnancy, parity, and circulating steroid hormone levels are associated with risk of breast cancer, but little is known about hormone concentrations during pregnancy and subsequent breast cancer risk. We evaluated early pregnancy (<140 days gestation) serum estradiol, estrone, progesterone, and testosterone and breast cancer risk in a nested case-control study in the Finnish Maternity Cohort. The cohort includes 98% of pregnancies registered in Finland since 1983. Individuals with samples collected in the first pregnancy leading to a live birth were eligible. Breast cancer cases (n = 1,199) were identified through linkage with the Finnish Cancer Registry; 2,281 matched controls were selected using incidence density sampling. ORs were calculated using conditional logistic regression. Hormone concentrations were not associated with breast cancer overall. Estradiol was positively associated with risk of breast cancer diagnosed age <40 [4th vs. 1st quartile OR 1.60 (1.07-2.39); Ptrend = 0.01], and inversely associated with breast cancer diagnosed at age ≥40 [4th vs. 1st quartile OR 0.71 (0.51-1.00); Ptrend = 0.02]. Elevated concentrations of the steroid hormones were associated with increased risk of estrogen receptor (ER)- and progesterone receptor (PR)-negative tumors in women age <40 at diagnosis. We observed no association between steroid hormones and ER(+)/PR(+) disease. These data suggest a positive association between high concentrations of early pregnancy steroid hormones and risk of ER(-)/PR(-) breast cancer in women diagnosed age <40, and an inverse association for overall breast cancer diagnosed age ≥40. Further research on pregnancy hormones and risk of steroid receptor-negative cancers is needed to further characterize this association.
authors.affiliation: Division of Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany. r.fortner@dkfz.de.
authors.forename: Renée T
authors.initials: RT
authors.lastname: Fortner
authors.affiliation: Division of Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Helena
authors.initials: H
authors.lastname: Schock
authors.affiliation: Division of Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Kaaks
authors.affiliation: School of Health Sciences, University of Tampere, Tampere, Finland.
authors.forename: Matti
authors.initials: M
authors.lastname: Lehtinen
authors.affiliation: School of Health Sciences, University of Tampere, Tampere, Finland. Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Helsinki, Finland.
authors.forename: Eero
authors.initials: E
authors.lastname: Pukkala
authors.affiliation: Department of Medical Biosciences, University of Umeå, Umeå, Sweden.
authors.forename: Hans-Åke
authors.initials: HÅ
authors.lastname: Lakso
authors.affiliation: Department of Oncology, Tampere University Hospital, Tampere, Finland.
authors.forename: Minna
authors.initials: M
authors.lastname: Tanner
authors.affiliation: Department of Oncology, Oulu University, Finland.
authors.forename: Raija
authors.initials: R
authors.lastname: Kallio
authors.affiliation: Department of Oncology, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland.
authors.forename: Heikki
authors.initials: H
authors.lastname: Joensuu
authors.affiliation: Department of Medical Biosciences, University of Umeå, Umeå, Sweden.
authors.forename: Kjell
authors.initials: K
authors.lastname: Grankvist
authors.affiliation: Department of Population Health, New York University School of Medicine, New York, New York. New York University Cancer Institute, New York University School of Medicine, New York, New York.
authors.forename: Anne
authors.initials: A
authors.lastname: Zeleniuch-Jacquotte
authors.affiliation: Department of Obstetrics and Gynecology, New York University School of Medicine, New York, New York.
authors.forename: Paolo
authors.initials: P
authors.lastname: Toniolo
authors.affiliation: Department of Medical Biosciences, University of Umeå, Umeå, Sweden. Public Health and Clinical Medicine: Nutritional Research, University of Umeå, Umeå, Sweden.
authors.forename: Eva
authors.initials: E
authors.lastname: Lundin
authors.affiliation: Unit of Sexual and Reproductive Health, National Institute for Health and Welfare, Oulu, Finland.
authors.forename: Helja-Marja
authors.initials: HM
authors.lastname: Surcel
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000097:blood* / Q000378:metabolism; D016022:Case-Control Studies; D018835:Chaperonin 10 / Q000097:blood* / Q000378:metabolism; D005260:Female; D005387:Finland; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006801:Humans; D008875:Middle Aged; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000097:blood* / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D012306:Risk; D012307:Risk Factors; D013491:Suppressor Factors, Immunologic / Q000097:blood* / Q000378:metabolism; D055815:Young Adult
chemical_list: D018835:Chaperonin 10; D012739:Gonadal Steroid Hormones; D011257:Pregnancy Proteins; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D013491:Suppressor Factors, Immunologic; C025124:early pregnancy factor