Cancer

Cancer is a class of diseases characterized by uncontrolled cell division and the ability of these cells to invade other biological networks, either by direct growth in adjacent tissue (invasion) or by migration of cells to distant places (metastasis). Uncontrolled growth is caused by damage to DNA, causing mutations in vital genes that control cell division. Some fruit mutation may be required to change normal cells into cancer cells. These mutations are often caused by chemical or physical agents called carcinogens. Mutations can occur spontaneously (obtained), or inherited (germline mutations). Cancer can cause many different symptoms, depending on its location and character of the malignancy and whether there is metastasis. A decisive diagnosis usually requires microscopic examination of tissue obtained by biopsy. Once diagnosed, cancer is usually treated with surgery, chemotherapy, or radiation.

If untreated, most cancers cause death, cancer is one of the main causes of death in developing countries. Most cancers can be treated and many cured, especially if treatment starts early. Many forms of cancer associated with environmental factors that could have been avoided. Tobacco smoking can cause cancer than many other environmental factors.

Tumors (Latin; swelling) appoint an abnormal tissue mass, but can be a "malignant" (cancerous) or "benign" (not cancerous). Only malignant tumors are capable of attacking other networks or metastasize. Cancer can spread through the lymph nodes or blood vessels to other organs