title: Limiting comorbid conditions and breast cancer stage at diagnosis.
abstract: BACKGROUND
  Contrasting hypotheses exist regarding the relationship between comorbidity and breast cancer stage at diagnosis. One suggestion is that disabling comorbid conditions would result in a later stage diagnosis of breast cancer because such conditions would limit mobility and thus access to medical care. This article examines this hypothesis by building a comorbidity summary measure of functionally limiting comorbid conditions and by testing the effectiveness of this measure in predicting the stage at which breast cancer is diagnosed.
  
  
  METHODS
  Cases with newly diagnosed breast cancer were identified through the population-based Metropolitan Detroit Cancer Surveillance System, a participant of the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute. Of 1191 eligible cases, 1011 (85%) were interviewed 2-4 months following diagnosis. The analyses for this study were limited to 731 cases for which there were complete data on all variables. Five individual comorbid conditions that predicted functional limitation were combined into a comorbidity summary measure: arthritis, eye conditions, gastrointestinal conditions, kidney conditions, and respiratory conditions. Breast cancer stage was categorized in relation to whether women had local or advanced (regional or remote) disease.
  
  
  RESULTS
  Women with two or more of these five functionally limiting conditions were about half as likely as those with none of these conditions to receive an advanced stage diagnosis of breast cancer (odds ratio [OR] = 0.49, 95% confidence interval [CI] 0.28-0.86, p = .01).
  
  
  CONCLUSIONS
  These findings do not support the suggestion that the presence of disabling comorbid conditions results in later stage breast cancer. The five conditions summarized by this measure, although functionally limiting, may also require greater medical monitoring due to associated symptoms and/or treatment requirements and thus lead to increased opportunities for cancer screening.
authors.affiliation: Division of Public Health Biology and Epidemiology, School of Public Health, University of California at Berkeley, USA. patrice.vaeth@utsouthwestern.edu
authors.forename: P A
authors.initials: PA
authors.lastname: Vaeth
authors.forename: W A
authors.initials: WA
authors.lastname: Satariano
authors.forename: D R
authors.initials: DR
authors.lastname: Ragland
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001168:Arthritis / Q000453:epidemiology; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000473:pathology*; D015897:Comorbidity; D005128:Eye Diseases / Q000453:epidemiology; D005260:Female; D005767:Gastrointestinal Diseases / Q000453:epidemiology; D006801:Humans; D007674:Kidney Diseases / Q000453:epidemiology; D008875:Middle Aged; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D015995:Prevalence; D011379:Prognosis; D012120:Respiration Disorders / Q000453:epidemiology