The Presence And Its Clinical Significance Of Circulating DNA In Primary Epithelial Ovarian Cancer

Objective:To explore the characteristic of circulating DNA in primary epithelial ovarian cancer(EOC) and its association with the expression of gene in tumor tissues. Methods:DNA was extracted by QIAamp DNA Mini Kit from plasma of 75 cases, including 35 patients with primary EOC, 20 patients with benign epithelial ovarian tumor and 20 healthy controls and the concentration of plasma DNA was dertermined by DNA DipStickTM Kit. We investiagted the possible relation of plasma DNA concentrations with the FIGO stage, histological grade, histological type and other parameters in primary EOC and its change after operation. The expression of p53, FHIT, nm23-Hl and survivin were examined by immunohistochemitry in the group of primary EOC and we analyzed the relationship of gene expression with the clinicopathological parameters and the amount of plasma DNA. Results:Average plasma DNA concentrations of primary EOC was 644.29ng/ml and significantly higher than that of benign epithelial ovarian tumor and healthy controls (88.95ng/ml and 15.25ng/ml, respectively). But there was obvious overlapped distribution range between primary EOC and benign epithelial ovarian tumor and we can't obtain a sure cutoff value for the differential diagnosis. The amount of plasmaDNA in primary EOC was significantly related with the existence of ascites, lymph node metastasis and the size of residual after operation. However, there was no significant correlation between the concentrations of plasma DNA and the FIGO stage, histological grade, histological type and the level of serum CA125. There are notabe decrease of plasma DNA concentrations after operation in primary EOC(422.29ng/ml on average, P<0.05). But the amount of plasma DNA in 11 cases didn't decrease significantly and rise at different levels after operation. Positive expression rate of p53, nm23-H1 and survivin protein in primary EOC was 54.29%, 68.57% and 60.00% respectively, and impaired expression of FHIT protein occurred in 6 cases(17.14%). Among all these changes, significant correlations were observed between FIGO stage and the expression of p53 and survivin protein, lymph node metastasis and the expression of nm23-Hl and FHIT protein, size of residual after operation and the expression of FHIT, nm23-Hl and survivin protein. Among all these four genes the amount of plasma DNA was only related with the expression of nm23-Hl gene in primary EOC. Conclusions:There is significant higher amount of plasma DNA in primary EOC comparing with benign ovarian tumor and healthy control, but it isn't enough to diagnose or screen primary EOC only by the concentrations of plasma DNA. The occurrence of circulating DNA is an early event because there was higher plasma DNA even in the early-stage primary EOC. The change of plasma DNA concentrations may be associated with the metastasis and tumor loading of EOC. Circulating DNA in plasma would be a useful marker for monitoring the progression and relapse of patients with primary EOC. Analysing its role in the judgement for the prognosis of patients with primary EOC may be helpful to better understand its clinical significance.