title: Reproductive history and risk of colorectal adenocarcinoma in parous women: a Nordic population-based case-control study.
abstract: BACKGROUND
  Data are conflicting regarding the role of endogenous sex hormones in colorectal carcinogenesis. In this large population-based study, we pooled data from birth and cancer registries in four Nordic countries, to evaluate the risk of colorectal adenocarcinoma in relation to women's reproductive history.
  
  
  METHODS
  We conducted a population-based case-control study among women registered in Nordic birth registries. The study included colorectal adenocarcinoma cases diagnosed in Denmark, Finland, Norway, and Sweden during 1967-2013 and up to 10 matched controls per case, in total 22 185 cases and 220 246 controls. Odds ratios (ORs) with 95% confidence intervals (95% CIs) were derived from conditional logistic regression models. We had limited information available on possible confounders.
  
  
  RESULTS
  We found no evidence for associations between colorectal adenocarcinoma and parity, age at first and last birth, and time since first and last birth. The risk estimates were also close to unity for specific cancer subsites (proximal and distal colon and rectum). As well, when the analyses were stratified on menopausal status, parity, and mother's year of birth, no indication of associations was found.
  
  
  CONCLUSIONS
  In this large, Nordic population-based study, no evidence for associations was found between women's reproductive history and colorectal adenocarcinoma in parous women.
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.|Cancer Registry of Norway, Oslo, Norway.
authors.forename: Tone
authors.initials: T
authors.lastname: Bjørge
authors.affiliation: National Institute for Health and Welfare (THL), Helsinki, Finland.
authors.forename: Mika
authors.initials: M
authors.lastname: Gissler
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Anne Gulbech
authors.initials: AG
authors.lastname: Ording
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.|Department of Pharmacoepidemiology, Division of Mental and Physical Health, Norwegian Institute of Public Health, Bergen/Oslo, Norway.
authors.forename: Anders
authors.initials: A
authors.lastname: Engeland
authors.affiliation: Department of Medicine, Clinical Epidemiology Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.|Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Glimelius
authors.affiliation: Cancer Society of Finland, Finnish Cancer Registry, Helsinki, Finland.
authors.forename: Maarit
authors.initials: M
authors.lastname: Leinonen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Henrik Toft
authors.initials: HT
authors.lastname: Sørensen
authors.affiliation: Cancer Registry of Norway, Oslo, Norway.
authors.forename: Steinar
authors.initials: S
authors.lastname: Tretli
authors.affiliation: Department of Medicine, Clinical Epidemiology Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Ekbom
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Troisi
authors.affiliation: Cancer Registry of Norway, Oslo, Norway.
authors.forename: Tom
authors.initials: T
authors.lastname: Grotmol
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology / Q000503:physiopathology*; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000503:physiopathology*; D005260:Female; D012739:Gonadal Steroid Hormones / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D010298:Parity; D011159:Population Surveillance; D011247:Pregnancy; D012307:Risk Factors; D012537:Scandinavian and Nordic Countries / Q000453:epidemiology
chemical_list: D012739:Gonadal Steroid Hormones