More than 95% of colorectal cancers come from adenocarcinoma polyps. These cancers start in cells that form mucus glands, which lubricate the colon and rectum. A polyp is a group of cells that form on top of each other and may eventually turn cancerous. Carcinoid tumors, gastrointestinal stromal tumors and lymphomas also cause 5% of [...]

Roughly 30% of middle-aged and older Americans have one or more polyps on the surface of the colon, which are relatively harmless but may become cancerous over time. While anyone can develop a polyp, some people are at higher risk of turning up with one during a bowel cancer screening, such as those over 50, [...]