title: Levels of C-peptide and mammographic breast density.
abstract: Members of the insulin-like growth factor family have been associated with breast cancer risk and mammographic breast density, one of the strongest known breast cancer risk indicators. The aim of this cross-sectional study was to examine the association of levels of C-peptide (a marker of insulin secretion) with mammographic breast density among 1,499 healthy women recruited during screening mammography examinations. At time of mammography, blood samples and time since last meal were collected. Plasma C-peptide levels were measured by ELISA method, and mammographic breast density by a computer-assisted method. Spearman's partial correlation coefficients, adjusting for age and time since last meal (when necessary), were used to evaluate the associations. High body mass index and waist-to-hip ratio measurements were independently correlated with high levels of C-peptide (r(s) = 0.173 and r(s) = 0.252, respectively; P < 0.0001) or low breast density (r(s) = -0.389 and r(s) = -0.142, respectively; P < 0.0001). High levels of C-peptide were correlated with low breast density (r(s) = -0.210, P < 0.0001). However, the strength of the negative correlation was substantially reduced and was no longer significant after further adjustment for body mass index and waist-to-hip ratio (r(s) = -0.022, P = 0.41). These results suggest that C-peptide levels are not associated with breast density after complete adjustment for adiposity. Thus, the insulin/C-peptide-breast density relation does not seem to mirror the insulin/C-peptide-breast cancer association.
authors.affiliation: Unité de recherche en santé des populations Centre hospitalier affilié universitaire de Québec, Hôpital Saint-Sacrement, 1050 Chemin Sainte-Foy, Quebec, Canada G1S 4L8.
authors.forename: Caroline
authors.initials: C
authors.lastname: Diorio
authors.forename: Michael
authors.initials: M
authors.lastname: Pollak
authors.forename: Celia
authors.initials: C
authors.lastname: Byrne
authors.forename: Benoît
authors.initials: B
authors.lastname: Mâsse
authors.forename: Nicole
authors.initials: N
authors.lastname: Hébert-Croteau
authors.forename: Martin
authors.initials: M
authors.lastname: Yaffe
authors.forename: Gary
authors.initials: G
authors.lastname: Coté
authors.forename: Sylvie
authors.initials: S
authors.lastname: Bérubé
authors.forename: Jacques
authors.initials: J
authors.lastname: Brisson
mesh_terms: D000273:Adipose Tissue; D000328:Adult; D015992:Body Mass Index; D001940:Breast / Q000033:anatomy & histology*; D001943:Breast Neoplasms / Q000097:blood* / Q000000981:diagnostic imaging*; D002096:C-Peptide / Q000097:blood*; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008327:Mammography; D008875:Middle Aged; D012307:Risk Factors
chemical_list: D002096:C-Peptide