Understanding Molecular Diagnosis in Cancer

The term diagnosis refers to a set of tests or investigations involving various biological samples such as tissue, body fluids and/or other irregularities in the body. While diagnosis is a broad term, examining the abnormalities in macromolecules - DNA, RNA or proteins at the level of nucleic acids and amino acids makes it a molecular diagnosis. As the world of diagnosis is rapidly expanding and advancing, newer minimal invasive techniques are being researched to spare the patients from various discomforts. Healthcare professionals are also aiming towards personalized medicine, making the treatment more selective and accurate, at the same time ensuring patients’ safety. This is being achieved by high throughput analysis, though currently still economically very challenging. Technologies such as Histopathology, Polymerase Chain Reaction (PCR), Flow Cytometry (FC), Immunohistochemistry (IHC), Capillary Electrophoresis (CE) and Fluorescent In Situ Hybridization (FISH) are already in use for routine diagnosis in cancer. Though, high throughput technologies like, Next Generation Sequencing (NGS), Microarray studies, miRNA detection, ChIP (Chromatin Immune-Precipitation) and MeDIP-seq (Methyl-DNA Immunoprecipitation), SELDI-TOF MS (Surface-Enhanced Laser Desorption/Ionization Timeof Flight Mass Spectrometry), quantitative proteomic analysis and many more are triumphing into the diagnostic avenue, they are restrictively catering to high socioeconomic groups in developing countries. An average citizen is still missing out on these forms of diagnosis and personalized treatments, thus devaluing the very aim of diagnosis and treatment in cancer. It becomes the pursuit of diagnostic community to come up with cost effective investigations and affordable treatments that could be efficiently validated. In this chapter, we briefly discuss the differences between diagnostic, prognostic and predictive tests along with a detailed understanding of genes and gene products that form the basis of molecular diagnosis in cancer. We also focus on currently available high-throughput methods and the challenges associated with them.

Keywords: Capillary Electrophoresis, ChIP, Flow Cytometry, Fluorescence in situ Hybridization, Gene Aberration, Histopathology, Immunohistochemistry, MeDIP-seq, Microarray, Molecular Diagnosis, Next Generation Sequencing, Polymerase Chain Reaction, SELDI-TOF MS.