AFP and osteosarcoma: Compared with well‐established tumor markers in other cancers, ALP in osteosarcoma showed similar sensitivity on diagnosis with alpha‐fetoprotein in hepatocellular carcinoma 28, 29 and carcinoembryonic antigen (CEA) and cytokeratin 19 fragment (CYFRA‐21) in lung cancer 30, 31, 32, for which sensitivity ranged from 39.0% to 68.6%.