title: Metformin Use Is Associated With Better Survival of Breast Cancer Patients With Diabetes: A Meta-Analysis.
abstract: BACKGROUND
  Diabetic patients with breast cancer receiving metformin and neoadjuvant chemotherapy have a higher pathologic complete response rate than do diabetic patients not receiving metformin, but findings on salvage treatment have been inconsistent. We performed a meta-analysis to assess the effect of adding metformin to standard therapy on the prognosis of breast cancer patients with diabetes.
  
  
  METHODS
  We searched PubMed, Embase, Web of Science (Thomson Scientific), China Knowledge Resource Integrated Database, VIP journal integration platform, and Chinese BioMedical Literature Database from inception to January 10, 2015, without language restrictions, including references related to metformin, breast cancer, and prognosis. We performed the meta-analysis using a random-effects model, with hazard ratios (HRs) and 95% confidence intervals (95% CIs) as effect measures.
  
  
  RESULTS
  A total of 11 studies consisting of 5,464 breast cancer patients with diabetes were included, comprising 2,760 patients who had received metformin and 2,704 patients who had not. The meta-analysis showed that metformin was associated with better overall survival times (HR: 0.53; 95% CI: 0.39-0.71) and cancer-specific survival times (HR: 0.89; 95% CI: 0.79-1.00). Subgroup analysis revealed that metformin improved the overall survival by 65% after adjusting for hormone receptor expression (HR: 0.35; 95% CI: 0.15-0.84). Taking metformin after the diagnosis of breast cancer was still associated with prolonged overall survival.
  
  
  CONCLUSIONS
  The use of metformin in standard cancer therapy might improve both overall and cancer-specific survivals of diabetic patients with breast cancer.
  
  
  CONCLUSIONS
  Diabetic patients with breast cancer receiving metformin and neoadjuvant chemotherapy have a higher pathologic complete response rate than diabetic patients not receiving metformin, but findings on salvage treatment have been inconsistent. The meta-analysis showed that metformin was associated with better overall survival times and cancer-specific survival times. Subgroup analysis revealed that metformin improved the overall survival by 65% after adjusting for hormone receptor expression. Taking metformin after the diagnosis of breast cancer was still associated with prolonged overall survival. The findings of this study highlight the potential usage of metformin in diabetic patients with breast cancer.
authors.affiliation: Department of Oncology, First Affiliated Hospital of Soochow University, Suzhou, People's Republic of China.
authors.forename: Hong
authors.initials: H
authors.lastname: Xu
authors.affiliation: Department of Oncology, First Affiliated Hospital of Soochow University, Suzhou, People's Republic of China.
authors.forename: Kai
authors.initials: K
authors.lastname: Chen
authors.affiliation: Department of Gastrointestinal Medical Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Jia
authors.affiliation: Department of Oncology, Suzhou Xiangcheng People's Hospital, Suzhou, People's Republic of China.
authors.forename: Yali
authors.initials: Y
authors.lastname: Tian
authors.affiliation: Department of Oncology, First Affiliated Hospital of Soochow University, Suzhou, People's Republic of China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Dai
authors.affiliation: Department of Oncology, First Affiliated Hospital of Soochow University, Suzhou, People's Republic of China.
authors.forename: Dapeng
authors.initials: D
authors.lastname: Li
authors.affiliation: Department of Oncology, First Affiliated Hospital of Soochow University, Suzhou, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Xie
authors.affiliation: Department of Oncology, First Affiliated Hospital of Soochow University, Suzhou, People's Republic of China Jiangsu Institute of Clinical Immunology, Suzhou, People's Republic of China maoyix@gmail.com mtao@medmail.com.cn.
authors.forename: Min
authors.initials: M
authors.lastname: Tao
authors.affiliation: Department of Oncology, First Affiliated Hospital of Soochow University, Suzhou, People's Republic of China Department of Gastrointestinal Medical Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA Jiangsu Institute of Clinical Immunology, Suzhou, People's Republic of China maoyix@gmail.com mtao@medmail.com.cn.
authors.forename: Yixiang
authors.initials: Y
authors.lastname: Mao
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy* / Q000453:epidemiology / Q000473:pathology; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000453:epidemiology / Q000473:pathology; D005260:Female; D006801:Humans; D008687:Metformin / Q000627:therapeutic use*; D020360:Neoadjuvant Therapy; D011379:Prognosis; D016019:Survival Analysis
chemical_list: D008687:Metformin
keywords: Breast cancer; Diabetes mellitus; Meta-analysis; Metformin; Survival