The correlation between plasma liver enzymes and the AUC of APC was unexpected, as it has been shown that CYP3A activity was reduced by 50% in patients with concurrent elevations in liver transaminases (Baker et al, 2004); however, it has also been shown that CYP3A4 expression was associated with the occurrence of metastases in osteosarcoma (Dhaini et al, 2003), which might explain why patients with high cortisol conversion into 6β-hydroxycortisol had altered liver enzymes. This evidence concerns the gene CYP3A4 and osteosarcoma.