Cancer occurs when cells become abnormal and keep dividing to form more cells without control or order, creating a mass of excess tissue called a tumor. Tumors can be malignant (cancerous) or benign (not cancerous). The cells in malignant tumors can invade and damage nearby tissue and organs. Cancer cells can also break away from a malignant tumor and travel through the bloodstream or lymphatic system to form new tumors in other parts of the body. A doctor may treat cancer with surgery, radiation therapy, chemotherapy, or other methods, depending on the type and location of the cancer, the patient's age and general health, and other factors. Many cancer patients take part in clinical trials (research studies) testing new methods designed to improve cancer treatment. |
