title: Hospital recorded morbidity and breast cancer incidence: a nationwide population-based case-control study.
abstract: BACKGROUND
  Chronic diseases and their complications may increase breast cancer risk through known or still unknown mechanisms, or by shared causes. The association between morbidities and breast cancer risk has not been studied in depth.
  
  
  METHODS
  Data on all Danish women aged 45 to 85 years, diagnosed with breast cancer between 1994 and 2008 and data on preceding morbidities were retrieved from nationwide medical registries. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression associating the Charlson comorbidity score (measured using both the original and an updated Charlson Comorbidity Index (CCI)) with incident breast cancer. Furthermore, we estimated associations between 202 morbidity categories and incident breast cancer, adjusting for multiple comparisons using empirical Bayes (EB) methods.
  
  
  RESULTS
  The study included 46,324 cases and 463,240 population controls. Increasing CCI score, up to a score of six, was associated with slightly increased breast cancer risk. Among the Charlson diseases, preceding moderate to severe renal disease (OR = 1.25, 95% CI: 1.06, 1.48), any tumor (OR = 1.17, 95% CI: 1.10, 1.25), moderate to severe liver disease (OR = 1.86, 95% CI: 1.32, 2.62), and metastatic solid tumors (OR = 1.49, 95% CI: 1.17, 1.89), were most strongly associated with subsequent breast cancer. Preceding myocardial infarction (OR = 0.89, 95% CI: 0.81, 0.99), connective tissue disease (OR = 0.87, 95% CI: 0.80, 0.94), and ulcer disease (OR = 0.91, 95% CI: 0.83, 0.99) were most strongly inversely associated with subsequent breast cancer. A history of breast disorders was associated with breast cancer after EB adjustment. Anemias were inversely associated with breast cancer, but the association was near null after EB adjustment.
  
  
  CONCLUSIONS
  There was no substantial association between morbidity measured with the CCI and breast cancer risk.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark. ao@dce.au.dk
authors.forename: Anne Gulbech
authors.initials: AG
authors.lastname: Ording
authors.forename: Jens Peter
authors.initials: JP
authors.lastname: Garne
authors.forename: Petra Mariann Witt
authors.initials: PM
authors.lastname: Nyström
authors.forename: Deirdre
authors.initials: D
authors.lastname: Cronin-Fenton
authors.forename: Maja
authors.initials: M
authors.lastname: Tarp
authors.forename: Henrik Toft
authors.initials: HT
authors.lastname: Sørensen
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Lash
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001499:Bayes Theorem; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000473:pathology; D016022:Case-Control Studies; D015897:Comorbidity; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008107:Liver Diseases / Q000453:epidemiology* / Q000473:pathology; D016015:Logistic Models; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology* / Q000473:pathology; D016017:Odds Ratio; D051436:Renal Insufficiency, Chronic / Q000453:epidemiology* / Q000473:pathology; D012107:Research Design; D012307:Risk Factors; D012720:Severity of Illness Index