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Development of cancer was proposed in 1971 to depend on at least two mutational events. In what became known as the Knudson two-hit hypothesis, an inherited, germ-line mutation in a tumor suppressor gene would cause cancer only if another mutation event occurred later in the organism's life, inactivating the other allele of that tumor ...
Hereditary cancers are primarily caused by an inherited genetic defect. A cancer syndrome or family cancer syndrome is a genetic disorder in which inherited genetic mutations in one or more genes predisposes the affected individuals to the development of cancers and may also cause the early onset of these cancers. Although cancer syndromes ...
Colon cancer provides one example of the mechanisms by which diet, the top factor listed in the table, is an external factor in cancer. The Western diet of African Americans in the United States is associated with a yearly colon cancer rate of 65 per 100,000 individuals, while the high fiber/low fat diet of rural Native Africans in South Africa is associated with a yearly colon cancer rate of ...
In non-inherited retinoblastoma, instead two mutations, or "hits", had to take place before a tumor could develop, explaining the later onset. It was later found that carcinogenesis (the development of cancer) depended both on the mutation of proto-oncogenes (genes that stimulate cell proliferation) and on the inactivation of tumor suppressor ...
A hereditary cancer syndrome (familial/family cancer syndrome, inherited cancer syndrome, cancer predisposition syndrome, cancer syndrome, etc.) is a genetic disorder in which inherited genetic mutations in one or more genes predispose the affected individuals to the development of cancer and may also cause early onset of these cancers.
In whole genome sequencing of different types of cancers, large numbers of mutations were found in two breast cancers (about 20,000 point mutations [43]), 25 melanomas (9,000 to 333,000 point mutations [44]) and a lung cancer (50,000 point mutations and 54,000 small additions and deletions [45]). Genome instability is also referred to as an ...
Other carcinogens may cause cancer through a variety of mechanisms without producing mutations, such as tumour promotion, immunosuppression that reduces the ability to fight cancer cells or pathogens that can cause cancer, disruption of the endocrine system (e.g. in breast cancer), tissue-specific toxicity, and inflammation (e.g. in colorectal ...
Deficient expression of DNA repair proteins due to an inherited mutation can increase cancer risks. Individuals with an inherited impairment in any of 34 DNA repair genes (see article DNA repair-deficiency disorder) have increased cancer risk, with some defects ensuring a 100% lifetime chance of cancer (e.g. p53 mutations). [113]