Causes & Risk occurrence of cancer

Cancer is a cell that has lost control and the normal mechanisms, so that growth is not regular.
Cancer can occur from various networks in various organs.
In line with the growth and breeding, cancer cells form a mass of malignant tissue to infiltrate nearby tissue and can spread (metastasize) to the entire body.

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

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

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

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

It may take a series of changes to the occurrence of cancer chromosomes.
Research on familial polyposis of colon (disorder hereditary form of colon polyp growth is transformed into malignant), has brought us to a suspicion 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 changes in the DNA minor facilitate the formation of adenoma (benign tumor).
Other genes (oncogenes RAS) causes adenoma grows more active.
Loss of suppressor genes on chromosome 18 next will stimulate adenoma and ultimately the loss of genes on chromosome 17 would change the benign adenoma into cancer.
Other additional changes can cause cancer to spread throughout the body (metastase).

By the time a cell becomes malignant, the immune system often can destroy malignant cells before it multiplied and became a cancer.
Cancers tend to occur when the immune system does not function normally, as happens in people. AIDS, people who use immune-suppressing drugs and in certain autoimmune diseases.
But the immune system is not always effective, the cancer can penetrate this protection even if the immune system function normally