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What is cancer?
Cancer is a disease where a group of cells in a part of the body begin to grow uncontrollably (by division of the cells beyond the normal limits) which causes a malignant growth or tumor. There are many kinds of cancer, but they all start due to out-of-control growth of abnormal cells due to damage to DNA. In a normal cell, when DNA is damaged, the cell either dies or repairs itself. Instead of dying off, cancer cells continue to grow and form new, abnormal cells. If the cancer invades other tissues (grows into other tissues) this is called metastasis. Most cancers form a tumor, except for leukemia, which does not. This type of cancer involves the blood and blood-forming organs and circulates through other tissues where they grow. If left untreated, cancer can cause serious illness and death.
Cancer affects people of all ages with the risk for most types of cancer increasing with age. Studies now indicate that cancers are primarily an environmental disease with 90-95% of cases due to lifestyle and environmental factors and 5-10% due to genetics. Common environmental factors leading to cancer include smoking, diet and obesity, infections, radiation, stress, environmental pollutants and lack of physical exercise. In some cases, there is no clear cause for the cancer. The process called metastasis happens when the cancer cells get into the bloodstream or lymph vessels of the body and travel to other parts of the body. No matter where a cancer spreads, it is always named for the place where it first started. As an example: prostate cancer that has spread to the lungs is metastaic prostate cancer - not lung cancer. Different cancers grow at different rates and respond to different treatments. Thus, people with cancer need treatment that is aimed at their particular type of cancer.
Definitive diagnosis of cancer requires the examination of a biopsy specimen. Once diagnosed, cancer is usually treated with a combination of surgery, radiation and chemotherapy. Most cancers can be treated and some forced into remission, depending on the stage of the cancer, the type and location. In recent years there has been significant progress in the development of drugs that are targeted to particular cancers, which minimize damage to normal cells.
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