Brief Summary: Chromosomal instability (CIN) refers to the ongoing genomic change, which involves the amplification or deletion of chromosome copy number or structure. The changes rang from point mutation to small-scale genomic change and even the change of whole chromosome number. It has been reported that the characteristics of genomic rearrangement can be used as a marker of clinical outcome of high-grade serous ovarian cancer, and specific genomic rearrangement are related to the poor prognosis. In noninvasive gene detection with low coverage, patients diagnosed with ovarian cancer have deteriorating progression-free and overall survivals regardless of the tumor stage when somatic copy number distortion (sCNA) exceeds the threshold in plasma. The detection rate of sCNA increased along with the tumor stage. We enrolled those as our target patients, who are diagnosed with high-grade serous ovarian cancer and willing to take part in. The CIN in peripheral cell-free DNA was observed before initial treatment, after primary debulking or staging surgeries, before recurrence and during the process of recurrence treatment. Our aim is to explore the application of CIN in peripheral tumor DNA in the detection of minimal residual lesions (MRD) after primary treatment and recurrence monitoring.

Detailed Description: