In early breast cancer, we found no association between ctDNA and 42 available paired primary tumours in respect to the promoter methylation status of these three genes (Table 3); concordance for SOX17 promoter methylation was observed in 19/42 (45.2%) cases while the concordances for CST6, and BRMS1 were very low. This evidence concerns the gene BRMS1 and neoplasm.