Colorectal cancer is cancer of the colon or rectum.
Cancer develops when the cells in the colon or rectum begin to grow and multiply in abnormal ways, forming tumors. Cancerous cells can attack and destroy your body's healthy cells. Colorectal cancer is the second leading cause of cancer deaths in the United States. It caused about 56,500 deaths in 1999. Many of these deaths happened because the cancers were found too late to be cured.