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Friday, April 15, 2011

Occurrence of Cancer Causes & Risks

Cancer is cells that have lost normal control mechanisms, so that the irregular growth.

Cancer can terjdi of various tissues in various organs.
In line with the growth and breeding, cancer cells form a mass of malignant tissue that infiltrate into nearby tissues and can spread (metastasize) throughout the body.

Cancer cells are formed from normal cells in a complex process called transformation, which consists of initiation and promotion stage.

At the initiation stage occurs a change in the genetic material of cells that provoke the cells become malignant.
Changes in the cell's genetic material is caused by an agency called carcinogens, which can include chemicals, viruses, radiation (irradiation) or sunlight.
But not all cells have the same sensitivity to a carcinogen. Genetic abnormalities in cells or other material which is called the promoter, causing the cells more susceptible to a carcinogen. Even the physical disruption menahunpun can make cells become more sensitive to having a malignancy.

At the stage of promotion, a cell that has undergone initiation will become malignant.
Cells that have not passed the stage of initiation is not affected by the campaign. Because it takes several factors for the occurrence of malignancies (combination of a sensitive cell and a carcinogen).

In a process in which a normal cell into a malignant cell, in the end the DNA of those cells will change.
Changes in the cell's genetic material is often hard to find, but the occurrence of cancer can sometimes be known from the existence of a change in size or shape of one particular chromosome.
For example, an abnormal chromosome called the Philadelphia chromosome found in about 80% of patients with chronic leukemia mielositik.
The genetic changes have also been found in brain tumors and colon cancer, breast, lung and bone.

It may take a series of chromosomal changes to the occurrence of cancer.
Research on familial polyposis of the colon (bowel disorder hereditary form of growth that turned into a malignant polyp), has brought us to a notion how this occurs in colon cancer.
The normal lining of the colon begin to grow actively (hiperproliferasi), because the cells no longer have the suppressor gene on chromosome 5 that under normal circumstances to control the growth of these layers.
Furthermore, mild changes in DNA facilitate the formation of adenomas (benign tumors).
Other genes (oncogenes RAS) causes adenoma grows 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 adenoma into cancer.
Other additional changes can cause cancer spread throughout the body (metastasis).

When a cell becomes malignant, the immune system can often spoil before these malignant cells multiply and become a cancer.
Cancer tends to occur if the immune system does not function normally, as happens in people. AIDS, people who use immune-suppressing drugs and in certain autoimmune diseases.
But not always effective immune system, cancer can penetrate this protection even if the immune system to function normally.

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