PTEN and neoplasm: indicated aberrant methylation status in twelve tumor-related genes of patients with VS, including RASSF1A, VHL, PTEN, TP16, CASP8, TIMP3, MGMT, DAPK, THBS1, HMLH1, TP73, and GSTP1. Among these genes, the RASSF1A methylation is inversely correlated with the clinical growth index, and methylation in CASP8 is associated with the patient's age and tumor size.