Fluorescent microsatellite analysis in bronchial lavage as a potential diagnostic tool for lung cancer

Cancer is a multistep progressive disease of increasing genomic instability. Genomic instability is a condition where the cell looses the ability to retain the semi-conservative means of its genome replication because of vital controlling mechanisms dysfunction. Thus, replication errors as well as large chromosomal lesions occur at high rates, giving rise to genetically diverse subpopulations, some of which have an increased growth advantage. These subpopulations evolve in the tissue microenvironment through natural selection processes that will enfavor cells carrying the most “advantageous” genetic lesions. Genomic instability is a phenomenon of all cancer cells and can be detected in two forms (1,2). Allelic imbalance (AI) or loss of heterozygosity (LOH) represents chromosomal instability (CIN) and involves a series of genetic phenomena like loss of chromosomal regions, duplication, DNA amplification, and aneuploidy. Solid tumor genomes exhibit gains and losses spread throughout chromosomes (3). Microsatellite instability (MIN, MI, or MSI), also found in the literature as replication errors (RER) or microsatellite alterations (MA), is most often attributed to DNA repair machinery errors (2).