In sarcomas with complex genomics, such as undifferentiated sarcoma and osteosarcoma, alterations in TP53 and/or the p53 pathway are frequently found: 22–66% in UPS and 47–90% in sporadic osteosarcoma [5,9,10,17,18,64]. This evidence concerns the gene TP53 and undifferentiated (embryonal) sarcoma.