Aberrant activation of oncogenes (eg, COPS3, PIK3CA, CARD11, MYC) and inactivation of tumour suppressor genes (eg, TP53, RB1, ATRX, DLG2, BRCA1/2) by somatic mutations and epigenetic mechanisms play a pivotal pathogenic role in osteosarcoma.26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37. This evidence concerns the gene PIK3CA and osteosarcoma.