Colorectal cancer is the abnormal growth of cancer cells in the
large intestine. Colon cancer forms in the longest part of the
large intestine, while rectal cancer forms in the last 8 in.
(20.3 cm) to 10 in. (25.4 cm) (rectum). Colon and rectal cancers
are often referred to together as colorectal cancer because they
have so much in common. Although the exact cause of colorectal
cancer is unknown, it almost always begins as small growths
called polyps inside the colon or rectum. Polyps can be found
with some screening tests and are often removed during the same
procedures. Colorectal cancer causes few symptoms in its early
stages. Symptoms are usually not noticed until later, when the
cancer is harder to treat. Symptoms include belly pain, a change
in bowel habits, bloody stools, stools that are narrower than
normal, unexplained weight loss, and fatigue. People are more
likely to develop colorectal cancer if they are older than 50,
have a family history of this cancer, or have rare inherited
colon cancer syndr