Furthermore, Van der Auwera et al. demonstrated that detection of methylated RASSF1A (29 %), adenomatous polyposis coli (APC) (35 %), or ER1 (20 %) correlated with the number of CTCs, enumerated by the CellSearch System, and thus indicates the CTC status in patients with metastatic BC [42]. This evidence concerns the gene RASSF1 and breast cancer.