Cancer - The Enemy Within
Abstract: Cancer has been known and feared since antiquity, but its imperative danger could only be realized until fairly recently. Indeed as knowledge of the disease grew in the nineteenth and twentieth centuries, fear increased when people became more aware that most cancers had no available cure. Cancer is a disease in which abnormal cells reproduce without control, destroy healthy tissue, and eventually cause deterioration to the body. This paper is a discussion on how cancer develops and spreads, some of the various types of cancer, and the causes of the disease.
Cancer is a disease in which cells multiply without control, ...view middle of the document...
These tissues form the body's supporting structures, such as bone and cartilage. The great majority of cancer cases are carcinomas. They include most cancers of the skin and the breast as well as of digestive, reproductive, respiratory, and urinary systems. Sarcomas also occur in all of these organs and systems but are far less common.
Scientists do not know exactly why cancer develops, but they have found that certain agents play an active role in causing the disease. Most experts agree that people develop cancer mainly through repeated or prolonged contact with one or more cancer-causing agents, called carcinogens. Carcinogens attack normal cells and may eventually cause one of them to become cancerous. Some carcinogens are introduced into the body through the nose, mouth, or some other opening. Other carcinogens attack the body through the skin. Many cancers are caused by a combination of 2 or more carcinogens rather than by a single one.
Laboratory tests and population studies indicate that two main groups of carcinogens can cause cancer in human beings. This groups consist of various chemicals, and certain forms of radiation. Some examples of chemical carcinogens include the tars in tobacco smoke, certain industrial chemicals, certain unnatural food chemicals and also various chemicals used in drugs. Radiation, on the other hand, produces cancer in people who are exposed to it for an extended periods of time. For instance, most cases of skin cancer are caused by ultraviolet rays from the sun. Also some x-ray machines and microwaves are cancer inducing as well.
Abnormal cell reproduction is the result of the development of cancer. The body of an adult human being is made up of hundreds of billion of cells. Each minute, several billion of these cells die and are replaced by several billion new cells. The new cells are produced by division. In this process, a cell divides and forms two identical cells. Each of these new cells then doubles in size and becomes capable of dividing. In this way, the new cells that are constantly being produced replace those that die. In addition, researchers have identified certain genes, called proto-oncogenes, that are vital to early tissue development. These genes may become changed or rearranged by chemicals or viruses. In this altered state, the genes are called oncogenes. The oncogenes then produce proteins that can transform a healthy cell into a cancerous cell. Normal cells reproduce at exactly the rate required to replace dying cells, never at a...