title: Diabetes mellitus and prognosis in women with breast cancer: A systematic review and meta-analysis.
abstract: BACKGROUND
  Diabetes mellitus is associated with an increased risk of breast cancer, but studies of the effects of diabetes on the prognosis of women with breast cancer have yielded inconsistent findings. The present meta-analysis aimed to investigate the impact of preexisting diabetes on the prognosis in terms of overall survival (OS), disease-free survival (DFS), and relapse-free period (RFP) in women with breast cancer.
  
  
  METHODS
  We searched the Embase and PubMed databases until June 2016 for cohort or case-control studies assessing the impact of diabetes on the prognosis of women with breast cancer. The pooled multivariate adjusted hazard ratio (HR) and their 95% confidence intervals (CIs) for OS, DFS, and RFP were used to analyze the impact of diabetes on the prognosis of breast cancer patients.
  
  
  RESULTS
  Seventeen studies involving 48,315 women with breast cancer met our predefined inclusion criteria. Meta-analysis showed that the pooled adjusted HR was 1.51 (95% CI 1.34-1.70) for OS and 1.28 (95% CI 1.09-1.50) for DFS in breast cancer patients with diabetes compared to those without diabetes. However, RFP did not differ significantly between patients with and without diabetes (HR 1.42; 95% CI 0.90-2.23).
  
  
  CONCLUSIONS
  The present meta-analysis suggests that preexisting diabetes is independently associated with poor OS and DFS in female breast cancer patients. However, the impact of diabetes on RFP should be further verified. More prospective studies are warranted to investigate whether appropriate glycemic control with modification of antihyperglycemic agents can improve the prognosis of female breast cancer patients with diabetes.
authors.affiliation: Chongqing Key Laboratory of Molecular Oncology and Epigenetics, The First Affiliated Hospital of Chongqing Medical University, Chongqing Department of Breast Surgery, Affiliated Hospital of North Sichuan Medical College, Nanchong Department of Endocrine and Breast Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Xiao-Bo
authors.initials: XB
authors.lastname: Zhao
authors.forename: Guo-Sheng
authors.initials: GS
authors.lastname: Ren
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000503:physiopathology; D002423:Cause of Death; D002681:China / Q000453:epidemiology; D015897:Comorbidity; D003920:Diabetes Mellitus / Q000453:epidemiology* / Q000503:physiopathology; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008875:Middle Aged; D015999:Multivariate Analysis; D015995:Prevalence; D011379:Prognosis; D016016:Proportional Hazards Models; D012016:Reference Values; D018570:Risk Assessment; D016019:Survival Analysis