Now, the antimetastatic activity of DNase I has been proven in a number of mouse tumor models; however, there are only a few studies where correlations were found between the decrease in the number of metastases, the decrease in blood cfDNA levels and the increase in DNase activity in the blood plasma [13,14,15,16,17,18,19,20]. The gene discussed is DNASE1; the disease is neoplasm.