Detection of aberrant methylation of four genes in plasma DNA for the detection of breast cancer.

PURPOSE Novel approaches to breast cancer screening are necessary, especially in the developing world where mammography is not feasible. In this study, we explored the hypothesis that blood-based biomarkers have potential for biomarkers for breast cancer. PATIENTS AND METHODS We first determined the frequency of aberrant methylation of four candidate genes (APC, GSTP1, Rassf1A, and RARbeta2) in primary breast cancer tissues from West African women with predominantly advanced cancers. We used a high-throughput DNA methylation assay (quantitative methylation-specific polymerase chain reaction) to examine plasma from 93 women with breast cancer and 76 controls for the presence of four methylated genes. Samples were randomly divided evenly into training and validation data sets. Cutoff values for gene positivity of the plasma-based assay and the gene panel were determined by receiver operating characteristic curves in the training data set and subsequently evaluated as a screening tool in the validation data set. RESULTS Methylation of at least one gene resulted in a sensitivity of 62% and a specificity of 87%. Moreover, the assay successfully detected 33% (eight of 24) of early-stage tumors. CONCLUSION These data suggest that epigenetic markers in plasma may be of interest for detection of breast cancer. Identification of additional breast cancer specific methylated genes with higher prevalence in early stage cancers would improve this approach.