Insulin-like Growth Factor-1, IGF-binding Protein-3, C-peptide and Colorectal Cancer: a Case-control Study

Context: Insulin-like growth factor peptides play important roles in regulating cell growth, cell differentiation,and apoptosis, and have been demonstrated to promote the development of colorectal cancer (CRC).
Objective: Toexamine the association of insulin-related biomarkers including insulin-like growth factor-1 (IGF-1), insulin-likegrowth factor binding protein-3 (IGFBP-3) and C-peptide with CRC risk and assess their relevance in predictivemodels. Materials and
Methods: The odds ratios of colorectal cancer for serum levels of IGF-1, IGFBP-3 andC-peptide were estimated using unconditional logistic regression models in 100 colorectal cancer cases and 100control subjects. Areas under the receiving curve (AUC) and integrated discrimination improvement (IDI)statistics were used to assess the discriminatory potential of the models.
Results: Serum levels of IGF-1 andIGFBP-3 were negatively associated with colorectal cancer risk (OR=0.07, 95%CI: 0.03-0.16, P for trend <.01,OR=0.06, 95%CI: 0.03-0.15, P for trend <.01 respectively) and serum C-peptide was positively associated withrisk of colorectal cancer (OR=4.38, 95%CI: 2.13-9.06, P for trend <.01). Compared to the risk model, predictionfor the risk of colorectal cancer had substantially improved when all selected biomarkers IGF-1, IGFBP-3 andinverse value of C-peptide were simultaneously included inthe reference model [P for AUC improvement was 0.02and the combined IDI reached 0.166% (95 % CI; 0.114-0.219)].
Conclusions: The results provide evidence foran association of insulin-related biomarkers with colorectal cancer risk and point to consideration as candidatepredictor markers.