Too much tissue is produced and tumors begin to form. Tumors can be either benign or malignant. Benign tumors are not cancer. They do not spread to other parts of the body and they are seldom a threat to life. Often, benign tumors can be removed by surgery, and they are not likely to return.
Malignant tumors are cancer.
They can invade and destroy nearby tissue and organs. Cancer cells also can spread, or metastasize, to other parts of the body, and form new tumors. Because cancer can spread, it is important for the doctor to find out as early as possible if a tumor is present and if it is cancer. As soon as a diagnosis is made, treatment can begin.