Cancer is a disease in which the body cells grow uncontrollably because their normal regulatory mechanisms have been damaged. There are literally hundreds of different types and subtypes of cancer however the majority form solid tumours in specific areas of the body. The most common cancers are skin cancer, breast cancer, lung cancer, bowel cancer and prostate cancer. Unfortunately the disease is very proficient at spreading through the blood and the lymphatic system and so in advanced cancer cases it is not uncommon to see secondary tumours in far off areas of the body.

The Genetics of Cancer

One of the most important breakthroughs in cancer research came in the late 1970s when scientists discovered that all types of cancer begin with the genetic material within normal body cells becoming damaged. Every cell contains genetic information in the form of more than 90,000 pairs of genes which work together to control the activities of the cell. A cell can become cancerous when specific genes, such as those that control division, become damaged beyond repair. How and why genes become damaged is still a hot topic for research however it would seem that faulty genes are either inherited or they are caused by carcinogens (cancer-causing agents), for example sunlight and cigarette smoke.

Our body cells are continually exposed to carcinogens however in the majority of cases cancer doesn't develop. There are a number of reasons why this is so, for example:

· Cells can normally repair their own damaged genes so that they continue to function properly. · More than one gene has to be damaged in order for cancer to develop. · The body's immune system can normally kill any cancer cells before they get the chance to multiply and form a tumour.

The Causes of Cancer

Although most cancers appear to be caused by several factors, including genetic/inherited ones, a main environmental cause can often be identified for a particular cancer i.e. smoking cigarettes is commonly associated with lung cancer.

Approximately 35% of stomach cancer and prostate cancer cases are related to diets of unhealthy foods with little or no fresh fruit and vegetables. 30% of lung, breast, colon, cervical and throat cancers are related to tobacco products such as cigarettes and cigars. 10% of skin cancer cases are related to the sun and UV rays. 7% of lymphoma, leukaemia, bone cancer and liver cancer cases are related to viruses such as Epstein Barr, HIV, Hepatitis C etc. Pesticides and chemicals, or occupational factors figure into 4% or mouth, throat, stomach and lymphoma cancer cases. Approx 3% of stomach, colon and liver cancer have been linked to excessive consumption of alchohol.

Aging and Cancer

Cancer is most common among older people, largely because their cells have had more time to accumulate genetic damage, but also because the body's defences against cancer, particularly the cells and proteins of the immune system, gradually become less efficient with age. In addition a cancer that began earlier in life may not be diagnosed until old age because it can take years for some types of cancer, most noticeably prostate cancer, to grow large enough to produce noticeable symptoms.

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