Genetic and Epigenetic Alterations in Cancer: Target Identification

Cancer is a heterogeneous and complex illness that is propelled by a variety of genetic and epigenetic changes affecting normal cellular homeostasis to permit uncontrolled growth, invasion, and metastasis. Variations in the genetic codes—its occurrence—occur by the means of genetic mutation—a substitution in a single nucleotide, insertion/deletion, copy number variation, and chromosomal rearrangements activate oncogenes or inactivate tumor suppressor genes. DNA methylation, histone mark modification, chromatin remodeling, as well as noncoding RNA dysregulation are some further modifications of transcriptional programs without affecting the DNA sequence in the form of epigenetic deregulation. Both classes of alteration can be used as biomarkers and therapeutic targets, with epigenetic regulators particularly being of interest given the reversibility in modifications. This chapter explains why these changes are at the molecular level, how they can be analyzed using approaches such as genomic sequencing, epigenomic profiling, and integration approaches, and what the most important examples of clinically relevant targets are. It also discusses the implications, limitations, and future prospects of precision oncology both therapeutically and other areas of its use.