Detection of Plasma Circulating Tumor DNA in Ovarian Cancer and Its Clinical Significance

To explore the application value of circulating tumor DNA in the diagnosis of benign and malignant ovarian tumors and its clinical significance in ovarian malignant tumors. A total of 70 patients with ovarian tumors who treated surgery in the first people's hospital of Lianyungang and the affiliated cancer hospital of Nanjing medical university from January 2017 to August 2020 were collected, including 32 cases of benign tumors, 15 cases of cross-sectional tumors, and 23 cases of malignant tumors. Venous blood was collected before the operation, and the expression level of the plasma circulating tumor DNA was detected by Next-Generation Sequencing, and the expression of circulating tumor DNA chromosome copy number variation in benign and malignant ovarian tumors was analyzed. At the same time, the relationship between the preoperative plasma circulating tumor DNA and clinicopathological features such as tumor size, clinical stage, histological grade, pathological type, and related immunohistochemical indexes were analyzed. There was a significant difference in preoperative plasma circulating tumor DNA among patients with benign, cross-sectional, and malignant tumors of the ovary (p<0.05). In terms of the clinical stage, there were 9 cases in the early stage group (I+II), 5 (55.56 %) cases were positive for plasma circulating tumor DNA before the operation. In the advanced stage group (III+IV), there were 14 cases, 12 (85.71 %) cases were positive for plasma circulating tumor DNA before the operation. In the histological grade of malignant ovarian cancer, there were 6 cases of ovarian low-grade cancer, of which 3 (50.0 %) cases were positive for plasma circulating tumor DNA before the operation. There were 17 cases of ovarian high-grade cancer, of which 14 (82.35 %) cases were positive for plasma circulating tumor DNA before the operation. Among the pathological types of tumors, there were 16 cases of plasma carcinoma and 14 (87.5 %) cases were positive for plasma circulating tumor DNA. There were 7 cases of non-plasma carcinoma and 3 (42.85 %) cases were positive for plasma circulating tumor DNA. In terms of tumor size, there were 7 cases with a diameter <10cm, of which 3 (42.85 %) cases were circulating tumor DNA positive. There were 16 cases of tumor diameter =10 cm, of which 14 (87.5 %) cases were circulating tumor DNA positive. In terms of pathological immunohistochemistry, among the 17 ovarian cancer patients with positive preoperative plasma circulating tumor DNA, there were 14 (82.35 %) patients with p53 mutation, and 3 (17.65 %) negative patients. There was no significant difference between the detection rate of plasma circulating tumor DNA and the immunohistochemical indexes such as Ki67, P16, estrogen receptor, progesterone receptor, and Wilms tumor protein-1 before the operation. Circulating tumor DNA level has a high predictive value for the disease progression in patients with ovarian cancer, and can be used as a reference index for clinical monitoring of patients' condition and prognosis.