title: Long-term all-cause mortality in cancer patients with preexisting diabetes mellitus: a systematic review and meta-analysis.
abstract: BACKGROUND
  Diabetes mellitus appears to be a risk factor for some cancers, but the effect of preexisting diabetes on all-cause mortality in newly diagnosed cancer patients is less clear.
  
  
  OBJECTIVE
  To perform a systematic review and meta-analysis comparing overall survival in cancer patients with and without preexisting diabetes.
  
  
  METHODS
  We searched MEDLINE and EMBASE through May 15, 2008, including references of qualifying articles.
  
  
  METHODS
  English-language, original investigations in humans with at least 3 months of follow-up were included. Titles, abstracts, and articles were reviewed by at least 2 independent readers. Of 7858 titles identified in our original search, 48 articles met our criteria.
  
  
  METHODS
  One reviewer performed a full abstraction and other reviewers verified accuracy. We contacted authors and obtained additional information for 3 articles with insufficient reported data.
  
  
  RESULTS
  Studies reporting cumulative survival rates were summarized qualitatively. Studies reporting Cox proportional hazard ratios (HRs) or Poisson relative risks were combined in a meta-analysis. A random-effects model meta-analysis of 23 articles showed that diabetes was associated with an increased mortality HR of 1.41 (95% confidence interval [CI], 1.28-1.55) compared with normoglycemic individuals across all cancer types. Subgroup analyses by type of cancer showed increased risk for cancers of the endometrium (HR, 1.76; 95% CI, 1.34-2.31), breast (HR, 1.61; 95% CI, 1.46-1.78), and colorectum (HR, 1.32; 95% CI, 1.24-1.41).
  
  
  CONCLUSIONS
  Patients diagnosed with cancer who have preexisting diabetes are at increased risk for long-term, all-cause mortality compared with those without diabetes.
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
authors.forename: Bethany B
authors.initials: BB
authors.lastname: Barone
authors.forename: Hsin-Chieh
authors.initials: HC
authors.lastname: Yeh
authors.forename: Claire F
authors.initials: CF
authors.lastname: Snyder
authors.forename: Kimberly S
authors.initials: KS
authors.lastname: Peairs
authors.forename: Kelly B
authors.initials: KB
authors.lastname: Stein
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Derr
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Wolff
authors.forename: Frederick L
authors.initials: FL
authors.lastname: Brancati
mesh_terms: D002423:Cause of Death; D015897:Comorbidity; D003920:Diabetes Mellitus / Q000453:epidemiology*; D006801:Humans; D009369:Neoplasms / Q000453:epidemiology / Q000401:mortality*; D012307:Risk Factors; D016019:Survival Analysis