IGF1 and osteosarcoma: In addition, the peak incidence of osteosarcoma correlates with the increased levels of growth hormone and IGF ligands in puberty, and it has been described that the expression of several IGF pathway members (IGF-1R, IGF-1, growth arrest-specific 6, and IGF binding proteins 4 [IGFBP4]) correlates with osteosarcoma prognosis [4, 7].