IGF1 and colorectal carcinoma: Comparison of serum IGF-1/IGFBP-3 concentrations (ELISA methods) in selected epidemiological studies in different stages of CRC and tissue expression of IGF-1, IGF-1R, and IGFBP-3 based on immunohistochemical or PCR techniques shows wide variation in serum concentrations and local expression of IGF axis components in vivo depending on studies, number of patients studied, and relatively poor correlation with clinical data [Table 1].