Class II tumor suppressor genes (C2TSGs) often become epigenetically silenced very early in the cancerous process leading from initiated cells to early tumors, late tumors and finally metastasis. Using “Liquid Biopsy” diagnostics, tumor cell derived methylated DNA can nowadays be detected with very high technical sensitivity as cell free DNA (cfDNA) in the blood stream of affected patients. Of course this requires sophisticated techniques like pyrosequencing, digital PCR or next generation sequencing. CfDNA from tumor cells is also referred to as ctDNA (tumor-derived cell free DNA). As Class II tumor suppressor genes become highly specifically methylated in tumor cells (compared to normal cells), finding methylated C2TSGs in blood-borne cfDNA is indicative of the presence of tumor cells in the patient. Our group is developing a four gene biomarker panel for early breast cancer detection, the so-called SNiPER Panel.