Cancer is caused by genetic mutations in somatic cells. Whole genome sequencing can identify all genetic alterations in cancer including single nucleotide mutations, small insertions/deletions, copy number changes, and chromosomal rearrangements. Earlier methods focused on sequencing protein kinase genes known to be involved in cancer signaling pathways. Current methods like whole exome sequencing focus on coding exons to identify damaging mutations at lower cost compared to whole genome sequencing. Non-coding mutations in regulatory regions and microRNAs are also important in cancer development.