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  • The cancer genomics era has been driven by rapid technological and computational advancements, which have enabled large-scale multidimensional analyses of rare and common cancers and precursor lesions.

  • The vast majority of human cancers are characterized by both inter- and intratumor molecular heterogeneity, which adds further complexity to the identification of robust and clinically useful biomarkers.

  • Clonal molecular evolution is evident throughout multiple stages of tumor development and has critical implications for the development of treatment resistance and metastasis.

  • Driven by the development of cost-effective and robust clinical next-generation sequencing (NGS) assays, somatic mutation profiling has been broadly integrated into clinical practice for patients with hematologic malignancies and advanced solid tumors. The long-term clinical benefit of comprehensive mutation profiling remains to be defined.

  • Despite the widespread application of tumor mutation profiling in practice, interpretation of the results and therapeutic decision making remains challenging. Institutional resources and/or publicly available decision tools should be consulted to help guide providers and patients.

  • Large-scale studies such as the NCI-MATCH study and the MD Anderson IMPACT study, provide a critical framework for matching patients with biomarker-driven clinical trials, which is a hallmark of precision oncology.


Over the past 50 years, multiple discoveries have had an impact on our understanding of key genomic events that influence the development of malignant growth. After many large-scale sequencing projects of cancer genomes, we now understand that many genetic alterations in specific cancer genes are responsible for the development and progression of the disease. These alterations may occur at the level of the patient's germline, predisposing to inherited forms of cancer that may develop in many tissues throughout the body. Genetic alterations may also be somatic, or newly acquired changes within the genes of an individual cell or group of cells over time, and a result of environmental stresses. Somatic alterations may come in many forms, including single-base substitutions, insertions or deletions of DNA fragments, rearrangements and rejoining of DNA from alternative locations in the genome, and copy number increases and reductions. Should these alterations affect key cancer genes, malignancy may develop.

In the early 1970s, the study of retroviruses that reverse transcribe RNA into DNA found that certain retroviruses, when incorporated into host cells, have the ability to transform normal cells into rapidly dividing tumors.1 Rous sarcoma virus, isolated by Peyton Rous, was the first retrovirus found to cause sarcoma in chickens.2 Later, hybridization studies proved that the Rous sarcoma virus gene, termed v-src, was homologous to a highly conserved eukaryotic gene, c-src. Src became the first known viral oncogene.3 In contrast to highly transforming retroviruses, weakly transforming viruses can insert themselves into the genome near proto-oncogenes—normal genes that when mutated give rise to an oncogene—and induce cancer. Activation of proto-oncogenes to oncogenes, through activating point mutations, gene amplification, or chromosomal translocation events, can occur independent of retroviral transformation and cause cancer.


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