title: The influence of comorbidities on overall survival among older women diagnosed with breast cancer.
abstract: BACKGROUND
  Previous studies have shown that summary measures of comorbid conditions are associated with decreased overall survival in breast cancer patients. However, less is known about associations between specific comorbid conditions on the survival of breast cancer patients.
  
  
  METHODS
  The Surveillance, Epidemiology, and End Results-Medicare database was used to identify primary breast cancers diagnosed from 1992 to 2000 among women aged 66 years or older. Inpatient, outpatient, and physician visits within the Medicare system were searched to determine the presence of 13 comorbid conditions present at the time of diagnosis. Overall survival was estimated using age-specific Kaplan-Meier curves, and mortality was estimated using Cox proportional hazards models adjusted for age, race and/or ethnicity, tumor stage, cancer prognostic markers, and treatment. All statistical tests were two-sided.
  
  
  RESULTS
  The study population included 64,034 patients with breast cancer diagnosed at a median age of 75 years. None of the selected comorbid conditions were identified in 37,306 (58%) of the 64,034 patients in the study population. Each of the 13 comorbid conditions examined was associated with decreased overall survival and increased mortality (from prior myocardial infarction, adjusted hazard ratio [HR] of death = 1.11, 95% CI = 1.03 to 1.19, P = .006; to liver disease, adjusted HR of death = 2.32, 95% CI = 1.97 to 2.73, P < .001). When patients of age 66-74 years were stratified by stage and individual comorbidity status, patients with each comorbid condition and a stage I tumor had similar or poorer overall survival compared with patients who had no comorbid conditions and stage II tumors.
  
  
  CONCLUSIONS
  In a US population of older breast cancer patients, 13 individual comorbid conditions were associated with decreased overall survival and increased mortality.
authors: Department of Epidemiology, Colorado School of Public Health, University of Colorado Denver, Aurora, CO 80045, USA. jenna.patnaik@gmail.com
authors: Jennifer L
authors: JL
authors: Patnaik
authors: Tim
authors: T
authors: Byers
authors: Carolyn
authors: C
authors: Diguiseppi
authors: Thomas D
authors: TD
authors: Denberg
authors: Dana
authors: D
authors: Dabelea
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000453:epidemiology / Q000401:mortality*; D015897:Comorbidity; D015986:Confounding Factors, Epidemiologic; D016208:Databases, Factual; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D006278:Medicare; D009026:Mortality / Q000639:trends; D016017:Odds Ratio; D011237:Predictive Value of Tests; D015995:Prevalence; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012307:Risk Factors; D018426:SEER Program; D014481:United States / Q000453:epidemiology