title: Colorectal cancer outcomes, recurrence, and complications in persons with and without diabetes mellitus: a systematic review and meta-analysis.
abstract: BACKGROUND
  Diabetes mellitus increases the risk of incident colorectal cancer, but it is less clear if pre-existing diabetes mellitus influences mortality outcomes, recurrence risk, and/or treatment-related complications in persons with colorectal cancer.
  
  
  METHODS
  We performed a systematic review and meta-analysis comparing colorectal cancer mortality outcomes, cancer recurrence, and treatment-related complications in persons with and without diabetes mellitus. We searched MEDLINE and EMBASE through October 1, 2008, including hand-searching references of qualifying articles. We included studies in English that evaluated diabetes mellitus and cancer treatment outcomes, prognosis, and/or mortality. The initial search identified 8,208 titles, of which 15 articles met inclusion criteria. Each article was abstracted by one author using a standardized form and re-reviewed by another author for accuracy. Authors graded quality based on pre-determined criteria.
  
  
  RESULTS
  We found significantly increased short-term perioperative mortality in persons with diabetes mellitus. In the meta-analysis of long-term mortality, persons with diabetes mellitus had a 32% increase in all-cause mortality compared to those without diabetes mellitus (95% CI: 1.24, 1.41). Although data on other outcomes are limited, available studies suggest that pre-existing diabetes mellitus predicts increased risk of some post-operative complications as well as 5-year cancer recurrence. In contrast, there is little evidence that diabetes confers increased risk for long-term cancer-specific mortality.
  
  
  CONCLUSIONS
  Patients with colorectal cancer and pre-existing diabetes mellitus have an increased risk of short- and long-term mortality. Future research should determine whether improvements in prevention and treatment of diabetes mellitus will improve outcomes for colorectal cancer patients.
authors.affiliation: Division of General Internal Medicine, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA. kbrunga1@jhmi.edu
authors.forename: Kelly B
authors.initials: KB
authors.lastname: Stein
authors.forename: Claire F
authors.initials: CF
authors.lastname: Snyder
authors.forename: Bethany B
authors.initials: BB
authors.lastname: Barone
authors.forename: Hsin-Chieh
authors.initials: HC
authors.lastname: Yeh
authors.forename: Kimberly S
authors.initials: KS
authors.lastname: Peairs
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: D016022:Case-Control Studies; D017024:Chemotherapy, Adjuvant; D003082:Colectomy / Q000379:methods; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D003131:Combined Modality Therapy; D003920:Diabetes Mellitus / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology* / Q000473:pathology; D009367:Neoplasm Staging; D012016:Reference Values; D018570:Risk Assessment; D016019:Survival Analysis; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology