When cells divide without control, they form too much tissue . The mass of extra tissue, called a tumor , can be benign or malignant . Benign tumors are not cancer. They do not spread to other parts of the body and are seldom a threat to life. Benign tumors can usually be removed by surgery, and they are not likely to return.
Malignant tumors are cancer.
They can invade and damage nearby healthy tissues and organs. Cancer cells can also break away from the tumor and enter the bloodstream or the lymphatic system . That is how cancer spreads and forms tumors in other parts of the body. The spread of cancer is called metastasis . Cancer of the esophagus is also called esophageal cancer.