You may know someone who has had cancer, and his or her hair fell out during treatment. When cells divide at an accelerated rate, they often begin to form a mass of tissue called a tumor . This factor stimulates the growth of an independent blood supply to the tumor. Tumors can also release substances that destroy tissues in close proximity to them. It is important to note that not all tumors are cancerous.
Tumors can be either malignant or benign.
A malignant tumor is cancer, and a benign tumor is not. A benign tumor is either surgically removed, or it may be left in place and simply observed to see what it does. The decision to remove or observe depends on the tumor's size, type and location. One of the frightening things about cancer is the possibility of metastasis. Other immune cells that battle malignant cells are macrophages, antigen-presenting cells, and substances produced by immune cells called lymphokines.