Liquid biopsy is challenging for the diagnosis of epithelial ovarian cancer (EOC). In this study, we performed the methylation testing of host DNA, namely, OPCML, FODX3 and CDH13, in the peripheral serum to discover the diagnostic and supervision roles of DNA methylation in EOC patients. The study compromises two stages.

In the training set, DNA methylation testing is performed in the ovarian tissues from EOC and paired benign ovarian tumor patients. The cut-off values of methylation are produced in this stage. On the meantime, serum DNA methylation testing is also performed to reveal its accordance and accuracy compared with the results of ovarian tissues.

In the validation set, serum DNA methylation testing is performed in unselected ovarian tumor patients with definite cut-off values to validate its accuracy based on known histology of ovarian tumors.

In training and validation sets, serum DNA methylation is also performed after major surgeries for EOC as to illustrate the changes of methylation testing, therefore, reflection the supervision role of DNA methylation.

Inclusion Criteria:

• With definite histological diagnosis of epithelial ovarian cancer and paired benign ovarian tumor in training set, and with definite histological diagnosis of ovarian tumor in validation set.
• With sufficient fresh peripheral serum and ovarian samples for DNA methylation testing before with or without after major surgeries.
• Aged 18 years or older.
• Signed an approved informed consents

Exclusion Criteria:

• Not meeting all of the inclusion criteria.