In this study we determined the plasma cfDNA concentration (by quantitative PCR and the fluorescence test) and analysed methylation of 6 genes (APC, FHIT, RASSF1, LRRC3B, VHL, and ITGA9 (Integrin α9β1)) in plasma samples from patients with kidney cancer in order to evaluate the diagnostic value of these markers for cancer detection. This evidence concerns the gene RASSF1 and cancer.