title: Glucocorticoid prescriptions and breast cancer recurrence: a Danish nationwide prospective cohort study.
abstract: BACKGROUND
  Treatment with synthetic glucocorticoids (GCs) depresses the immune response and may therefore modify cancer outcomes. We investigated the association between GC use and breast cancer recurrence.
  
  
  METHODS
  We conducted a population-based cohort study to examine the risk of breast cancer recurrence associated with GC use among incident stage I-III female breast cancer patients aged >18 years diagnosed 1996-2003 in Denmark. Data on patients, clinical and treatment factors, recurrence, and comorbidities as well as data on GC prescriptions and potential confounders were obtained from Danish population-based medical registries. GCs were categorized according to administrative route: systemic, inhaled, or intestinal. Women were followed for up to 10 years or until 31 December 2008. We used Cox proportional hazards regression models to compute hazard ratios (HRs) and associated 95% confidence intervals (95% CIs) to evaluate the association between GC use and recurrence. Time-varying drug exposures were lagged by 1 year.
  
  
  RESULTS
  We included 18 251 breast cancer patients. Median recurrence follow-up was 6.9 years; 3408 women developed recurrence during follow-up. Four thousand six hundred two women filled at least one GC prescription after diagnosis. In unadjusted models, no association was observed among users of systemic, inhaled, and intestinal GCs (HRsystemic = 1.1, 95% CI 0.9-1.3; HRinhaled = 0.9, 95% CI 0.7-1.0; and HRintestinal = 1.0, 95% CI 0.9-1.2) versus nonusers. In adjusted models, the results were also near null (HRsystemic = 1.1, 95% CI 0.9-1.2; HRinhaled = 0.8, 95% CI 0.7-1.0; and HRintestinal = 1.0, 95% CI 0.8-1.2).
  
  
  CONCLUSIONS
  We found no evidence of an effect of GC use on breast cancer recurrence.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark. Electronic address: lwl@clin.au.dk.
authors.forename: L W
authors.initials: LW
authors.lastname: Lietzen
authors.affiliation: Departments of Surgery and Biochemistry, College of Medicine, University of Vermont, Burlington.
authors.forename: T
authors.initials: T
authors.lastname: Ahern
authors.affiliation: Department of Surgery.
authors.forename: P
authors.initials: P
authors.lastname: Christiansen
authors.affiliation: Department of Oncology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: A B
authors.initials: AB
authors.lastname: Jensen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: H T
authors.initials: HT
authors.lastname: Sørensen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark; Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, USA.
authors.forename: T L
authors.initials: TL
authors.lastname: Lash
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: D P
authors.initials: DP
authors.lastname: Cronin-Fenton
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000473:pathology*; D003718:Denmark; D005260:Female; D005938:Glucocorticoids / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence
chemical_list: D005938:Glucocorticoids
keywords: breast neoplasm; epidemiology; glucocorticoids; outcome