This prospective observational study is to assess the dynamics of circulating tumor DNA (ctDNA) in patients with advanced epithelial ovarian cancer (EOC) undergoing surgery, adjuvant chemotherapy, followed by poly adenosine diphosphate-ribose polymerase (PARP) inhibitors until disease progression or the end of the study. All patients will be closely monitored throughout the course of disease by a tumor-informed bespoke ctDNA assay as well as traditional methods of surveillance, such as CA125 and imaging. This study may provide preliminary evidence for ctDNA-guided treatment decisions in future clinical practice.

This observational study is designed for exploring prognostic and predictive values of the tumor-informed bespoke ctDNA assay in advanced EOC. Newly diagnosed patients who are eligible for radical surgery or relapsed patients from platinum-based adjuvant chemotherapy who are eligible for secondary cytoreductive surgery will be enrolled. The patients will be treated with SOC adjuvant therapies followed by PARP inhibitor for maintenance.

To evaluate ctDNA dynamics, tumor tissue collected from surgery will be sequenced with whole-exome sequencing (WES) to design patient-specific 16-plex panel. At planned monitoring timepoints, blood samples will be drawn, and ctDNA will be sequenced with ultra-deep ctDNA high-throughput sequencing methods.

Traditional surveillance methods will be applied as comparison, including but not limited to carbohydrate antigen 125 (CA-125)/ human epididymal protein 4 (HE4)/ carcinoembryonic antigen (CEA)/ carbohydrate antigen 199 (CA199), etc., as well as standard imaging.

Survival analyses will be conducted based on ctDNA status (positive/negative) after surgery. Recurrence rate of each subgroup, positive predictive values and negative predictive values etc. will be examined. Changes in ctDNA levels (ΔctDNA) during treatment will be used to evaluate the efficacy of maintenance therapy comparing traditional biomarkers,

Inclusion Criteria:

1. Female, over 18 years of age;
2. Patients with advanced epithelial ovarian cancer who are eligible for radical surgery;
3. Patients with advanced epithelial ovarian cancer relapsed from platinum-based therapies and eligible for secondary cytoreductive surgery;
4. The subjects agree to sign the informed consent and agree to use their samples and data for related scientific research;
5. Subjects agree to collect tissue samples and peripheral blood samples for whole exon sequencing and ctDNA monitoring.

Exclusion Criteria:

1. Patients who are diagnosed, tested or treated for cancer other than ovarian cancer within 2 years (except for basal skin or squamous cell cancer that has been definitively treated);
2. Patients in pregnancy;
3. Patients with a history of blood transfusion within 3 months before enrollment;
4. Newly diagnosed patients who only received laparoscopic surgery;
5. Patients received chemotherapy or other anti-tumor therapy before surgery.

Self-representation of gender identity

Newly diagnosed advanced EOC patients who are eligible for radical surgery or relapsed EOC patients from platinum-based adjuvant chemotherapy who are eligible for secondary cytoreductive surgery.