title: Mortality after incident cancer in people with and without type 2 diabetes: impact of metformin on survival.
abstract: OBJECTIVE
  Type 2 diabetes is associated with an increased risk of several types of cancer and with reduced survival after cancer diagnosis. We examined the hypotheses that survival after a diagnosis of solid-tumor cancer is reduced in those with diabetes when compared with those without diabetes, and that treatment with metformin influences survival after cancer diagnosis.
  
  
  METHODS
  Data were obtained from >350 U.K. primary care practices in a retrospective cohort study. All individuals with or without diabetes who developed a first tumor after January 1990 were identified and records were followed to December 2009. Diabetes was further stratified by treatment regimen. Cox proportional hazards models were used to compare all-cause mortality from all cancers and from specific cancers.
  
  
  RESULTS
  Of 112,408 eligible individuals, 8,392 (7.5%) had type 2 diabetes. Cancer mortality was increased in those with diabetes, compared with those without (hazard ratio 1.09 [95% CI 1.06-1.13]). Mortality was increased in those with breast (1.32 [1.17-1.49]) and prostate cancer (1.19 [1.08-1.31]) but decreased in lung cancer (0.84 [0.77-0.92]). When analyzed by diabetes therapy, mortality was increased relative to nondiabetes in those on monotherapy with sulfonylureas (1.13 [1.05-1.21]) or insulin (1.13 [1.01-1.27]) but reduced in those on metformin monotherapy (0.85 [0.78-0.93]).
  
  
  CONCLUSIONS
  This study confirmed that type 2 diabetes was associated with poorer prognosis after incident cancer, but that the association varied according to diabetes therapy and cancer site. Metformin was associated with survival benefit both in comparison with other treatments for diabetes and in comparison with a nondiabetic population.
authors.affiliation: Department of Primary Care and Public Health, School ofMedicine, Cardiff University, Cardiff, UK. currie@cardiff.ac.uk
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Currie
authors.forename: Chris D
authors.initials: CD
authors.lastname: Poole
authors.forename: Sara
authors.initials: S
authors.lastname: Jenkins-Jones
authors.forename: Edwin A M
authors.initials: EA
authors.lastname: Gale
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Johnson
authors.forename: Christopher Ll
authors.initials: CL
authors.lastname: Morgan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000453:epidemiology / Q000401:mortality; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000009:adverse effects* / Q000627:therapeutic use*; D008297:Male; D008687:Metformin / Q000009:adverse effects* / Q000627:therapeutic use*; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology / Q000401:mortality*; D011471:Prostatic Neoplasms / Q000453:epidemiology / Q000401:mortality; D012189:Retrospective Studies
chemical_list: D007004:Hypoglycemic Agents; D008687:Metformin