Purpose The lack of early detection assays and the occurrence of unspecific symptoms are causative for the late diagnosis of EOC. Aberrant DNA methylation of cell-free DNA (cfDNA) in blood may be a potential biomarker for EOC.
Methods Genome wide methylation analyses of tissue-derived gDNA and cfDNA from blood were used to identify candidate regions. Marker validation was realized with two sample sets by methylation specific PCR (MSP) using bisulfite-treated cfDNA (set 1: benign controls n=67 (leiomyoma, endometriosis, cysts) and EOC n=68 (FIGO III/IV); set 2: EOC n=43 (FIGO I-IV) and age matched healthy women n=14).
Results Analyses of tissues (EOC n=33, normal ovaries n=3, white blood cells n=4) lead to the identification of potential candidates (n=50). Three top candidates reached a sensitivity and specificity of 33-51% and 91-100%, respectively. The best two-marker combination exhibited 62.7% sensitivity and 96.3% specificity. Low methylation level in the tumor tissue, intratumoral heterogeneity and a low methylation frequency in early stage disease may explain the sub-optimal sensitivity. To identify additional markers the genome wide analysis of cfDNA was established and conducted. The detected candidates are presently validated and may increase the sensitivity of a final marker panel.
Conclusion The specific and sensitive detection of EOC-specific aberrant DNA methylation in cfDNA is possible. Detection strategies and assays for final candidates will be optimized which should result in an improved diagnostic performance of DNA-methylation-based biomarkers.
