Causes And Effects Of Cancer

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Cancer is a name given to collection of various diseases that are caused by a similar mechanism: uncontrolled division of cells that results in formation of abnormal cells that grow without stopping - tumors. Cancer is caused by changes in genes of the cells that control the way they function. Those changes can be caused by various environmental factors, such as excess ultraviolet exposure from the sun, chemicals in tobacco smoke, radiation from radioactive elements and many other factors. The only type of cancer that can be caused by an infection is the viral cancer. Viruses that cause cancer are called oncoviruses; oncoviruses represent approximately 15% of all human cancers worldwide (Liao 115). Viruses are made up of small portion of either DNA or RNA(sometimes both) surrounded by a protein coat. Viruses enter a living cell and insert portion of their DNA or RNA into the host cell, allowing the host cell to reproduce even more viruses through the processes of transcription and translation of the cell. Each type of viruses tends to be very specific: they target only specific type of cells in the body. Even though development of cancerous tumors from viral infections may take years or even decades, they are still causing thousands of deaths annually (Liao 43).
A tremendous portion of human cancers are associated with viral infections: “The estimated total of infection-attributable cancer in the year 2002 is 1.9 million cases, or 17.8% of the global cancer burden. The

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