title: Plasma C-peptide, insulin-like growth factor-I, insulin-like growth factor binding proteins and risk of colorectal cancer in a nested case-control study: the Japan public health center-based prospective study.
abstract: The physical inactivity and obesity involved in hyperglycemia and hyperinsulinemia is supposed to lead to an increased bioavailability of insulin-like growth factor-I (IGF-I). The carcinogenic effect of IGF-I may be influenced by IGF binding proteins. We investigated the association between plasma levels of C-peptide, a surrogate biomarker of insulin, IGFBP-1, IGF-I or IGFBP-3, and the risk of colorectal cancer in a nested case-control study. During an 11.5-year follow-up, 375 newly diagnosed colorectal cancers were identified in a cohort of 38,373 adults who had returned the baseline questionnaire and provided blood samples. Two matched-controls for each case were selected from the cohort. The odds ratio (OR) of colorectal cancer for plasma levels of each protein was estimated using the conditional logistic regression model adjusted for potential confounding factors. We observed a statistically significant association of plasma C-peptide with colorectal cancer only in men. The ORs were 1.0, 2.3, 2.8 and 3.2 along with quartiles (p trend, 0.0072). The association was stronger in colon cancer (p trend, 0.025) than in rectal cancer (p trend, 0.24). Other peptides were not associated with the risk in either men or women. The results did not change when repeatedly analyzed by tumor invasion levels, tumor sites or follow-up periods. In conclusion, a higher plasma C-peptide may indicate a subsequent risk of colorectal cancer in Japanese men.
authors.affiliation: Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Otani
authors.forename: Motoki
authors.initials: M
authors.lastname: Iwasaki
authors.forename: Shizuka
authors.initials: S
authors.lastname: Sasazuki
authors.forename: Manami
authors.initials: M
authors.lastname: Inoue
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Tsugane
mesh_terms: D000328:Adult; D000368:Aged; D002096:C-Peptide / Q000097:blood*; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000097:blood* / Q000209:etiology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
chemical_list: D002096:C-Peptide; D018970:Insulin-Like Growth Factor Binding Protein 1; D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I