Uncontrolled growth of cells that tend to invade neighboring tissue and metastasize at a distance. Each cancer is distinguished by its nature, location, or clinical course of the lesion. The primary cause of cancer has not been established, though many potential factors have been detected, such as smoking, exposure to ultraviolet rays, and exposure to certain chemical agents or radiations.
Surgery is still the main mode of treatment but irradiation or administration of chemotherapy is widely used as treatment before and after surgery, and is very effective.