title: Relationship of obesity and physical activity with C-peptide, leptin, and insulin-like growth factors in breast cancer survivors.
abstract: BACKGROUND
  Obese and physically inactive breast cancer patients may have poorer survival compared with lighter weight and more active women. Several obesity-related and physical activity-related hormones and peptides may explain this association, including insulin, leptin, insulin-like growth factor-I (IGF-I), and IGF-binding protein-3. Few studies have examined the associations between obesity, physical activity, and these hormones/peptides among breast cancer survivors.
  
  
  OBJECTIVE
  To determine whether obesity and physical activity are associated with insulin, IGFs, and leptin levels in a population-based sample of 710 women diagnosed with in situ to stage IIIA breast cancer and enrolled in the Health, Eating, Activity, and Lifestyle Study.
  
  
  METHODS
  We collected a blood sample and information on physical activity among women diagnosed 2 to 3 years earlier using an interview-administered questionnaire. Trained staff measured weight. C-peptide, leptin, and IGFs were assayed by RIA. Mean hormone levels within body mass index and physical activity categories were adjusted for confounders using analysis of covariance methods.
  
  
  RESULTS
  We observed higher C-peptide (P for trend = 0.0001) and leptin (P for trend = 0.0001) levels and lower IGF-I levels (P for trend = 0.0001) with higher levels of body mass index. We observed lower C-peptide (P for trend = 0.001) and leptin (P for trend = 0.001) levels and higher IGF-I (P for trend = 0.0037) and IGF-binding protein-3 (P for trend = 0.055) levels with higher levels of physical activity.
  
  
  CONCLUSIONS
  Increasing physical activity and decreasing body fat may be a reasonable intervention approach toward changing insulin and leptin, thereby potentially influencing breast cancer prognosis.
authors.affiliation: Department of Epidemiology and Public Health, Yale School of Medicine, P.O. Box 208034, New Haven, CT 06520-8034, USA. melinda.irwin@yale.edu
authors.forename: Melinda L
authors.initials: ML
authors.lastname: Irwin
authors.forename: Anne
authors.initials: A
authors.lastname: McTiernan
authors.forename: Leslie
authors.initials: L
authors.lastname: Bernstein
authors.forename: Frank D
authors.initials: FD
authors.lastname: Gilliland
authors.forename: Richard
authors.initials: R
authors.lastname: Baumgartner
authors.forename: Kathy
authors.initials: K
authors.lastname: Baumgartner
authors.forename: Rachel
authors.initials: R
authors.lastname: Ballard-Barbash
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D014408:Biomarkers, Tumor / Q000097:blood; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000097:blood* / Q000150:complications; D002096:C-Peptide / Q000097:blood*; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D020738:Leptin / Q000097:blood*; D008875:Middle Aged; D009043:Motor Activity; D009765:Obesity / Q000097:blood* / Q000150:complications; D011446:Prospective Studies; D017741:Survivors
chemical_list: D014408:Biomarkers, Tumor; D002096:C-Peptide; D018972:Insulin-Like Growth Factor Binding Protein 3; D020738:Leptin