The old theories that explain the pathophysiology of cancer progression include contagious diseases spread by parasites. Later advent concept was trauma and chronic inflammation leading to cancer progression. But medical science advancement brought the concept of genetics and genomics in cancer development. In 1962, Watson & Crick discovered DNA structure and oncogenes. In 1970, the discovery of genetics and genomics had happened.
The basic concept of genetics and genomics is based on genetics, gene mutation, and cancer genomics. The study of genes and the hereditary characteristics of living organisms that transfer to one generation another are termed genetics. Permanent alteration of the DNA sequence that makes up a gene is called a genetic mutation. In many cases, cancer progression is based on genetic mutation. Cancer genomics is the study to identify the difference in DNA sequence and gene expression between tumor cells and healthy cells.
Clonal expansion of cells due to genomic changes conversing malignant properties is now a broadly accepted concept of cancer development. The cancer genomic concept can explain both inherited and somatic cancers context. Understanding cancer genomics help to precise testing for cancer and tumor diagnosis. Subsequently, it emphasizes therapeutic decision-making.
Cancer genetics and genomics explain the various mechanisms that cells adapt to become cancer cells. Experts can understand the cellular pathway which deviates the cell from normal constraints on proliferation to transform into tumor cells. Identification of the involvement of genes and cellular pathways helps to identify the novel targets for therapeutic intervention. This also assists in the identification of biomarkers for better diagnosis, staging, and risk assessment for individual cancer patients.
The ongoing process of the development of a new treatment regimen for cancer takes part through several laboratories and pre-clinical studies based on cancer genetics and genomics. These studies help in
- Detection and isolation of the novel genes that is important in the development of specific cancers.
- Application of human oncogenes concept to the clinical management of cancer patients
- Investigation of epigenetic mechanisms that affect gene function and
- Genomics approaches allow studying global genetic changes in cancer cells. This could help to understand the naturally occurring genetic variation responsible for the predisposition and progression of cancer in near future.
- Doctors can detect how many mutations a tumor has by conducting genomic testing. This is termed as tumor mutational burden (TMB).
- Doctors can also recognize the instability of a tumor by detecting the range of microsatellite instability or have “MSI-H” status. “MSI-H” status can explain the clusters of genetic errors.
- Immunotherapy works better against both TMB-H and MSI-H tumors. The FDA has approved two immunotherapies to treat all types of advanced cancers with the identification of genetic markers without considering the origin of cancer location. The reason immunotherapy works better against these tumors is due to the mutated genes are captured as a “foreign” body in the immune system.
References:
https://www.sciencedirect.com/science/article/pii/B9780124201965000204
https://pubmed.ncbi.nlm.nih.gov/12610533/
https://www.roswellpark.org/research/departments/cancer-genetics-genomics
https://www.cancerresearch.org/blog/june-2020/genetics-genomics-cancer-care-immunotherapy
