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Cancers

Cancer is a group of related diseases that begin in cells, according to the National Cancer Institute (2000). It is the result of uncontrolled growth of cells in the body and their ability to migrate from their site of origin to distant parts of the body (Cherath, 1999). Cancer is second largest cause of death after heart disease in the United States. There are different types of cancers: carcinomas which start in the epithelium, and account for about 90 percent of human cancers; melanomas, which start in the pigment cells (the melanocytes); sarcomas, which start in the supporting cells of the body such as muscles and bones; cancers of the nerve cells called gliomas; and cancers of the blood (leukemias) and the lymph tissue (lymphomas) (Cherath, 1999). These are malignant tumors, where the cells keep dividing uncontrollably and can damage the tissues and organs they invade. Malignant tumors also spread to other parts of the body when cells break off and get carried away in the bloodstream (National Cancer Institute, 2000). Benign tumors are not cancer and do not spread or usually pose a threat to life.

Cancer is not contagious, and though it is often hard to find an exact cause for a particular cancer, there are many risk factors which are recognized as making people more prone to getting cancer. These include lifestyle (smoking, alcohol use, diet, sexual practices), the environment (ultraviolet radiation, radon exposure, carcinogenic chemicals in the workplace or environment, air pollution), and heredity.

Many scientists believe that genetic factors play a major role in causing cancer, and indeed the evidence is building as more and more forms of cancer are linked to the presence of specific genes or the absence of specific tumor-suppressors. The genes that play a major role in causing cancer are of two types called oncogenes and tumor-suppressor genes (Haber and Fearon, 1998). Oncogenes were first discovered in bir...

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Cancers. (1969, December 31). In LotsofEssays.com. Retrieved 00:50, March 29, 2024, from https://www.lotsofessays.com/viewpaper/1687601.html