This study is a prospective observational clinical trial. Patients who were diagnosed and treated for the first time were enrolled and their surgical pathology was confirmed to be high-grade serous ovarian cancer. At the same time, these patients will receive first-line maintenance treatment with PARP inhibitors after traditional chemotherapy. During the trial period, patients' plasma will be collected before surgery, after chemotherapy, during targeted maintenance therapy, and during disease progression, and ctDNA-specific genomes will be detected, and clinical data will be collected over the same period. It is expected that specific ctDNA can be used to predict the efficacy of PARP inhibitors in patients with ovarian cancer, and to detect the recurrence of the disease early.

Inclusion Criteria:

1. Ovarian cancer first diagnosed and treated;
2. Pathologically confirmed as epithelial ovarian cancer/fallopian tube cancer/primary peritoneal cancer;
3. The stage of the disease is II-IV, and surgery will be performed after evaluation;
4. Age ≥ 18 years old;
5. Subjects and their families fully understand the research plan and sign an informed consent form.

Exclusion Criteria:

1. Pathologically confirmed as non-epithelial ovarian cancer;
2. Surgical treatment cannot be performed after evaluation;
3. Malignant tumors found in other parts of the study were found within five years before enrollment or at the time of enrollment;
4. Patients who do not agree to use clinical first-line targeted drugs;
5. Severe mental illness;
6. Severe cardiovascular disease, uncontrollable infection, or other uncontrollable comorbid diseases.

Newly-diagnosed and treated patients with high-grade serous ovarian cancer who will receive PARP inhibitors as first-line maintenance therapy after surgery and traditional chemotherapy.