Definition of colon cancer: Cancer that forms in the tissues of the colon (the longest part of the large intestine). Most colon cancers are adenocarcinomas (cancers that begin in cells that make and release mucus and other fluids).
Estimated new cases and deaths from colon and rectal cancer in the United States in 2011:

New cases: 101,340 (colon); 39,870 (rectal)
Deaths: 49,380 (colon and rectal combined)