What is colorectal cancer?
Colorectal cancer is cancer that develops in the tissues of the colon and/or rectum. The colon and the rectum are both found in the lower part of the gastrointestinal (digestive) system. They form a long, muscular tube called the large intestine (or large bowel). The colon absorbs food and water and stores waste. The rectum is responsible for passing waste from the body.
If the cancer began in the colon, which is the first four to five feet of the large intestine, it may be referred to as colon cancer. If the cancer began in the rectum, which is the last several inches of the large intestine leading to the anus, it is called rectal cancer.
Colorectal cancer starts in the inner lining of the colon and/or rectum, slowly growing through some or all of its layers. It typically starts as a growth of tissue called a polyp. A particular type of polyp, called an adenoma, can then develop into cancer.
Colorectal cancer incidence
Colorectal cancer is the fourth most common form of cancer (or third, excluding skin cancers) in both men and women in the United States. The American Cancer Society estimated that 143,460 people will be diagnosed with colorectal cancer in 2012.