title: Association between insulin resistance and breast carcinoma: a systematic review and meta-analysis.
abstract: OBJECTIVE
  This study was undertaken to evaluate the association between components defining insulin resistance and breast cancer in women.
  
  
  METHODS
  We conducted a systematic review of four databases (PubMed-Medline, EMBASE, Web of Science, and Scopus) for observational studies evaluating components defining insulin resistance in women with and without breast cancer. A meta-analysis of the association between insulin resistance components and breast cancer was performed using random effects models.
  
  
  RESULTS
  Twenty-two studies (n = 33,405) were selected. Fasting insulin levels were not different between women with and without breast cancer (standardized mean difference, SMD -0.03, 95%CI -0.32 to 0.27; p = 0.9). Similarly, non-fasting/fasting C-peptide levels were not different between the two groups (mean difference, MD 0.07, -0.21 to 0.34; p = 0.6). Using individual odds ratios (ORs) adjusted at least for age, there was no higher risk of breast cancer when upper quartiles were compared with the lowest quartile (Q1) of fasting insulin levels (OR Q2 vs. Q1 0.96, 0.71 to 1.28; OR Q3 vs. Q1 1.22, 0.91 to 1.64; OR Q4 vs. Q1 0.98, 0.70 to 1.38). Likewise, there were no differences for quartiles of non-fasting/fasting C-peptide levels (OR Q2 vs. Q1 1.12, 0.91 to 1.37; OR Q3 vs. Q1 1.20, 0.91 to 1.59; OR Q4 vs. Q1 1.40, 1.03 to 1.92). Homeostatic model assessment (HOMA-IR) levels in breast cancer patients were significantly higher than in people without breast cancer (MD 0.22, 0.13 to 0.31, p<0.00001).
  
  
  CONCLUSIONS
  Higher levels of fasting insulin or non-fasting/fasting C-peptide are not associated with breast cancer in women. HOMA-IR levels are slightly higher in women with breast cancer.
authors.affiliation: Instituto Médico de la Mujer/Instituto Médico Metabólico, Lima, Peru; Postgraduate and Medical Schools, Universidad Peruana de Ciencias Aplicadas (UPC), Lima, Peru; Health Outcomes and Clinical Epidemiology Section, Department of Quantitative Health Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America.
authors.forename: Adrian V
authors.initials: AV
authors.lastname: Hernandez
authors.affiliation: Instituto Médico de la Mujer/Instituto Médico Metabólico, Lima, Peru.
authors.forename: Mirella
authors.initials: M
authors.lastname: Guarnizo
authors.affiliation: Instituto Médico de la Mujer/Instituto Médico Metabólico, Lima, Peru.
authors.forename: Yony
authors.initials: Y
authors.lastname: Miranda
authors.affiliation: Department of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America.
authors.forename: Vinay
authors.initials: V
authors.lastname: Pasupuleti
authors.affiliation: Department of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America; Department of Medicine, Medicine Institute, Cleveland Clinic, Cleveland, Ohio, United States of America.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Deshpande
authors.affiliation: Instituto Médico de la Mujer/Instituto Médico Metabólico, Lima, Peru.
authors.forename: Socorro
authors.initials: S
authors.lastname: Paico
authors.affiliation: Instituto Médico de la Mujer/Instituto Médico Metabólico, Lima, Peru.
authors.forename: Hosten
authors.initials: H
authors.lastname: Lenti
authors.affiliation: Instituto Médico de la Mujer/Instituto Médico Metabólico, Lima, Peru.
authors.forename: Silvia
authors.initials: S
authors.lastname: Ganoza
authors.affiliation: Instituto Médico de la Mujer/Instituto Médico Metabólico, Lima, Peru.
authors.forename: Laritza
authors.initials: L
authors.lastname: Montalvo
authors.affiliation: Department of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America.
authors.forename: Priyaleela
authors.initials: P
authors.lastname: Thota
authors.affiliation: Instituto Médico de la Mujer/Instituto Médico Metabólico, Lima, Peru.
authors.forename: Herbert
authors.initials: H
authors.lastname: Lazaro
mesh_terms: D001943:Breast Neoplasms / Q000453:epidemiology* / Q000378:metabolism*; D002096:C-Peptide / Q000097:blood; D005215:Fasting; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D016017:Odds Ratio; D017594:Publication Bias
chemical_list: D002096:C-Peptide; D007328:Insulin