Cancer is a general term used to refer to a condition where the body’s cells begin to grow and reproduce in an uncontrollable way. These cells can then invade and destroy healthy tissue, including organs. Cancer sometimes begins in one part of the body before spreading to other parts.
invasiveness of surrounding tissues, and metastasis, or spreading via the lymph system or blood to other tissues and organs. Whereas normal cells have a limited lifespan controlled by the telomere gene, which signals the end of the cell line, cancer cells contain telomerase, an enzyme that alters the telomere gene and allows the cell to continue to divide. Cancer tissue, growing without limits, competes with normal tissue for nutrients, eventually killing normal cells by nutritional deprivation. Cancerous tissue can also cause secondary effects, in which the expanding malignant growth puts pressure on surrounding tissue or organs or the cancer cells metastasize and invade other organs.