Real-time Fluorescence Quantitative PCR In Detection Of Circulating DNA In Plasma From Patients With Lung Cancer And Its Potential Clinical Significance

Purpose To quantify the circulating DNA in plasma from patients with lung cancer and evaluate its potential clinical significance.Methods Blood samples were collected from 80 patients with lung cancer,40 benign lung disease patients and 97 healthy controls.Plasma DNA was extracted and purified by"genomic DNA extraction kit".The quantitation of the plasma DNA was performed by real-time fluorescence quantitative PCR assay. Screening performance of the assay was calculated through the receiver operating characteristic (ROC) curve.Results The median concentration of circulating plasma DNA in lung cancer was 19.85 ng/ml, which was significantly higher (P=0.000) than that of the patients with benign lung disease (4.6ng/ml) and the healthy controls (3.2 ng/ml).Early in stage I, the amount of circulating plasma DNA has increased to 14.7 ng/ml, which was three times higher than the patients with benign lung disease and four times higher than health individuals (P=0.003). The area under the ROC curve was 0.879 (95%CI,0.830～0.928). With a threshold value of 10.75ng/ml, the overall sensitivity of the assay was 82.6%, specificity was 84.7%.The median concentration of circulating plasma DNA was closely related to its cTNM stage,tumor size and serum CYFRA21-1 (P=0.028, P=0.027, P=0.006) ,but not to the pathological type,tumor type,histological grade and leukocyte counts (P=0.786, P=0.658, P=0.772,P=0.068) .The median plasma DNA concentration in post-surgery samples was significantly lower than that in pre-surgery samples(P=0.001),but no decreasing or increasing was found in patients with cancer relapse(P=0.893).Conclusion Circulating plasma DNA quantification may be a useful marker for screening and early diagnosis of lung cancer,and for monitoring the therapeutic efficacy and recurrence...