DNA Diagnosis in Oncology

It is well established that cancers are caused by the accumulation of genomic and epigenomic alterations. However, molecular changes occuring in the early stages of cancer development or in precursor lesions remain to be poorly understood.The employment of molecular characterization of tumors prior to therapy has opened the door for personalized therapy of individual patients. Such genetic alterations that are utilized to predict response to therapy are considered predictive biomarkers. The development of high throughput technologies lead to the establishment of a relatively new field of cancer genomics. These genome-wide approaches are increasingly more important in cancer diagnostic, prognosis, and treatment. Here we briefly discuss cancer transcriptome, cancer genome and epigenome analyses approches and their clinical utility. Gene expression patterns in tumors (cancer transcriptome) are analyzed by expression microarrays who can serve as a diagnostic tool which facilitates distinguishing different cancer subtypes. Another high throughput technology that may revolutionize personalized cancer therapy, lead to the development of new genetic diagnostic tests and biomarkers is next generation sequencing (NGS). NGS has an ability to fully sequence large number of genes in a single test and simultaneously detect deletions, insertions, copy number alterations, translocations and exome-wide base substitutions in cancer-related genes. NGS methods analyses DNA methylation, detection of modified histones, mapping of transcription factor occupancy, and epigenetic regulators. DNA diagnosis often trumps clinical diagnosis in oncology. This will cause the shift toward testing minute amounts of DNA and specimens including needle biopsies, circulating tumor cells, and ciruclating cell-free DNA are likely to become clinically relevant. Thus, as NGS enters clinical testing it will impact clinical decisions and cancer outcomes. Finally, improved understanding of cancer biology will lead to further development of targeted therapies and the use of combinations of targeted approaches simultaneously, increasing treatment effectiveness and supporting highly individualized patient care.