Sunday, June 13, 2010

Mechanism of occurrence of cancer (2)

Genetic changes have also been found in brain tumors and colon cancer, breast, lung, and bone. It may take a series of chromosomal changes prior to the occurrence of cancer. Research on poliposis familial colon (congenital abnormalities of the growth of colon polyps that turned into dangerous), has brought allegations of how this happens in colon cancer. Layer of normal colon begin to grow actively (hiperproliferasi) because their cells no longer have the suppressor gene on chromosome 5 that under normal circumstances to control the growth of the layer. Further minor changes in DNA facilitate the formation of adenomas (benign tumors).
Other genes (oncogenes RAS) causes adenomas to grow more active.

Loss of suppressor genes on chromosome 18 will further stimulate adenoma and ultimately the loss of genes on chromosome 17 would change the benign adenomas become dangerous. Other additional changes can cause cancer to spread widely throughout the body (metastases).

When a cell becomes dangerous, damaging the immune system can often be dangerous before the cells multiply and become a cancer.

Cancer tends to occur when the immune system does not operate normally, as happens in people with HIV / AIDS, people who use immunosuppressant drugs and on certain autonium disease. However, the immune system is not always effective so that cancer can penetrate this protection even if the immune system function normally.

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