Cancer Genetics

Cancer is a genetic disease of somatic cells. Knudsons hypothesis confirmed the role of genetic predisposition in certain cancers. Penetrance depends upon additional, somatic, mutations. The increase in cell number and insensitivity to apoptotic signals is responsible for causing cancer. Tumor karyotypes are rarely normal, and most show multiple abnormalities of both number and structure. In the past two decades or so, more than 30 mutant genes for such hereditary cancers have been cloned. A few of the genes are oncogenes or DNA repair genes, but most are tumor suppressor genes. Some tumor suppressors regulate transcription, while others operate in signal transduction pathways that are involved in regulating processes of cell birth, differentiation, and death. In addition to these gatekeeper genes, there are some caretaker genes which are involved to maintain the integrity of genome. Mutations in these can also cause cancer. Telomerase activity has also been shown in 90% of human cancers. The knowledge gained is stimulating new approaches to the treatment and prevention of cancer. The model of Genetic cancer risk assessment (GCRA) must be supplemented with next generation interactive teaching and counseling aids, more ef cient means to collect and interpret family history as well as genomic and environmental risk information.