title: Effect of metformin on survival outcomes in diabetic patients with triple receptor-negative breast cancer.
abstract: BACKGROUND
  Recent observational studies have shown that metformin use in diabetic patients decreases both cancer incidence and mortality. Metformin use is also independently predictive of pathologic complete response. In the current study, the authors explored the association between metformin use and survival outcomes in patients with triple receptor-negative breast cancer (TNBC) who were receiving adjuvant chemotherapy.
  
  
  METHODS
  The Breast Cancer Management System database of The University of Texas MD Anderson Cancer Center identified 1448 women who received adjuvant chemotherapy for TNBC between 1995 and 2007. Patients were categorized by diabetes status and metformin use. The Kaplan-Meier product-limit method was used to calculate distant metastasis-free survival (DMFS), recurrence-free survival (RFS), and overall survival (OS). Cox proportional hazards models were fit to determine the association between metformin use and survival outcomes.
  
  
  RESULTS
  The study cohort was comprised of 63 diabetic patients receiving treatment with metformin, 67 diabetic patients not receiving metformin, and 1318 nondiabetic patients. Patients in the diabetic groups tended to be older (P = .005); more diabetic patients were postmenopausal (P = .0007), black (P = .0001), and obese (P < .0001). At a median follow-up of 62 months, there were no significant differences with regard to 5-year DMFS (P = .23), RFS (P = .38), and OS (P = .58) between the 3 groups. Compared with the metformin group, patients who did not receive metformin (hazard ratio [HR], 1.63; 95% confidence interval [95% CI], 0.87-3.06 [P = .13]) and nondiabetic patients (HR, 1.62; 95% CI, 0.97-2.71 [P = .06]) tended to have a higher risk of distant metastases.
  
  
  CONCLUSIONS
  The findings of the current study suggest that metformin use during adjuvant chemotherapy does not significantly impact survival outcomes in diabetic patients with TNBC.
authors.affiliation: Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030-4009, USA.
authors.forename: Soley
authors.initials: S
authors.lastname: Bayraktar
authors.forename: Leonel F
authors.initials: LF
authors.lastname: Hernadez-Aya
authors.forename: Xiudong
authors.initials: X
authors.lastname: Lei
authors.forename: Funda
authors.initials: F
authors.lastname: Meric-Bernstam
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Litton
authors.forename: Limin
authors.initials: L
authors.lastname: Hsu
authors.forename: Gabriel N
authors.initials: GN
authors.lastname: Hortobagyi
authors.forename: Ana M
authors.initials: AM
authors.lastname: Gonzalez-Angulo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000150:complications / Q000188:drug therapy / Q000378:metabolism / Q000401:mortality*; D002277:Carcinoma / Q000150:complications / Q000188:drug therapy / Q000378:metabolism / Q000401:mortality*; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000188:drug therapy* / Q000401:mortality*; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D008687:Metformin / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use*; D008875:Middle Aged; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D007004:Hypoglycemic Agents; D018160:Receptors, Cytoplasmic and Nuclear; D008687:Metformin