Tumors occur when new cells in the body are produced in an uncontrolled and unorderly manner. Normally, body cells grow and produce new cells to replace dead cells. However, sometimes, new cells are formed when they are not supposed to and old cells don't die when they should. When these extra cells aggregate to form a mass, it is called a tumor.
Tumors can be generally classified as either benign or malignant. Benign tumors are not cancerous while malignant tumors are cancerous, which means they can spread to nearby organs or even other body parts. In benign tumors, the tumor cells grow only in one place and do not invade nearby organs or other parts of the body. However, benign tumors can press on nearby vital organs. For example, a benign tumor that forms in the brain can press on other structures of the brain.
Treatment of benign tumors usually involves surgery. Once benign tumors are removed, they usually do not grow back.
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What is Cancer? (National Cancer Institute)
Tumor Grade: Questions and Answers (National Cancer Institute)
Tumor Grade: Questions and Answers (National Cancer Institute)
