Circulating tumor DNA in plasma of breast cancer patients from India

Abstract

e22213 Background: Recently, breast cancer has become the most common cancer among women in all urban population in India. Annually about 80000 new cases and 40000 deaths occur and majority of breast cancers are pre-menopausal. Conventional diagnostic methods are not very sensitive especially in early stages of cancer. This necessitated a more sensitive and reliable method for early diagnosis leading to effective treatment, better prognosis and survival. Recently, the level of cell free circulating tumor DNA in blood plasma or serum of patients with variety of tumors are being considered as reliable non-invasive diagnostic tool but no study has been done in India. The present study has therefore been undertaken to evaluate clinical utility of cell free DNA as potential biomarkers for early diagnosis and management of breast cancer. Methods: 25 newly diagnosed untreated breast cancer patients and 25 healthy subjects having no sign of significant medical illness with informed consent were enrolled for the study. 9 patients after chemotherapy were also included in the study. Blood plasma collected from both patients and controls were employed for DNA isolation, using Qiagen kit. Concentration of cell free plasma DNA was analyzed by 3 methods viz. nanodrop spectro-photometry, integrated density value (IDV) of PCR products of Exon 7 of p53 gene and quantitative real time PCR (cycles threshold converted to genome equivalent). All values of DNA concentration obtained by three methods used as continuous variables and receiver operating characteristic (ROC) were plotted and the cut-of value was determined at 90% sensitivity and 100% specificity level of ROC. Results: Mean free plasma DNA concentration as determined by both Q-RT PCR and IDV in cancer patients was found to be significantly higher in advanced stage breast cancer patients than in controls (genome equivalent 18850 vs 431; IDV 17912 vs 4197; p=0.001). However, no significant difference could be observed in early stage disease as compared to controls possibly due small sample size. Conclusions: Free Plasma DNA concentration is a reliable molecular marker for detection of breast cancer and can serve as a prognostic indicator leading to its potential clinical application either alone or in combination with other conventional methods. No significant financial relationships to disclose.