To identify noninvasive breast cancer-specific biomarkers, the methylation levels of circulating CCDC181, GCM2, ITPRIPL1, LOC643719, ZNF177, ENPP2, ADCY4 and RASSF1 were determined in each 200 μL plasma sample from 22 healthy and 45 breast cancer patients. Here, ENPP2 is linked to breast cancer.