Agents From the environment , such as chemicals drugs, depacco smoke, radiation, and viruses, can cause damage to DNA and thus produce cancer. These environmental agents are called carcinogens.
Heredity
Cancer may be caused not only by environmental factors but also by inherited factors examples are retinoblastoma (tumor of the retina of the eye ) polyposis coil syndrome (polyps that grow in the colon and rectum) and certain other forms of colon , breast , and kidney cancer
| GENES IMPLICATED IN HEREDITARY CANCERS | ||
| Cancer | Gene | Chromosomal Location |
| Breast ; Ovarian | BRCA1 | 17q21 |
| Breast | BRCA2 | 13q12-13 |
| Polyposis Coil Sybdrome | APC | 5q21 |
| Li-Fraument(multiple cancers) | P53 | 17p13 |
| Retinoblastoma | Rb1 | 13q14 |
| Wilms tumor | WT1 | 11p13 |
The first number is the chromosome ; p is the short arm of the chromosome and q is the long arm of the chromosome ; the second number is the religion (band) of the chromosome
In many, it belived that these tumors arise because of inherited or acquired abnormalites in certain genes called suppressor genes. Examples of suppressor genes are the retinoblastoma gene (Rb-1) and the p53 gene
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