the colon is the large intestine and the rectum is the last six inches of intestine connecting the colon to the anus. in the u. s. for both sexes about 72% of cancer cases occur in the colon and 28% in the rectum. colorectal cancer usually develops slowly beginning first as a small growth called a polyp. polyps may grow larger and eventually turn into cancer. the entire process of a polyp transforming into cancer usually takes several years. after cancer develops it grows into the wall of the colon and eventually metastasizes or spreads. most of the time this process is preventable with proper screening. colorectal cancer symptoms include a change in bowel habits (diarrhea or constipation) blood in the stool black stools abdominal pain and weakness.
what is colorectal cancer?