Study On Detection For Plasma DNA In Lung Cancer Patients

Tumor-released DNA in blood represents a promising biomarker for cancer diagnosis. It has been supposed that tumor necrosis causes release of DNA of varying sizes, which contrasts apoptosis in normal tissue that releases smaller and more uniform DNA fragments .To test the hypothesis that increased DNA integrity, ie, a longer DNA stand is a tumor-associated marker in plasma DNA .We determined the genomic DNA integrity index in plasma DNA, using real-time PCR assay. A DNA integrity index and DNA concentration in plasma were determined in 45 patients with lung cancer and 45 patients without neoplastic disease. We found the median DNA integrity index in the neoplastic group was significantly higher than that in the noneoplastic group(p<0.0001),under the receiver-operating characteristic curve ,given 100% specificity, the highest sensitivity achieved in detecting the cancer group was 67%(95%confidence interval=0.54~0.74)at the index cutoff of 0.59 ,55.6%percents stage â…  cancers had a DNA integrity index above this cutoff.72.2% stage â…¡ and above stage â…¡ cancers had a DNA integrity index above this cutoff. Our findings suggest that increased DNA integrity in plasma is associated with cancer, and measurement of DNA integrity may provide a simple and inexpensive measure for cancer detection.