In [10] the authors did indeed use a test set to evaluate potential biomarkers (promotor methylation of the tumour-suppressor genes SFRP1, SFRP2, SFRP5, ITIH5, WIF1, DKK3 and RASSF1A in cfDNA extracted from serum) for blood-based breast cancer screening. Here, DKK3 is linked to breast cancer.