The colon (also called the large intestine or large bowel) is a muscular tube that forms the last part of the digestive tract. It absorbs water and stores food waste. The colon is about 4 to 6 feet long and the rectum makes up the last 6 inches. The colon and rectum have a smooth lining composed of millions of cells.
Changes in these cells can lead to the growth of polyps on the lining of the colon. Most are benign (non-‐ cancerous). But over time, polyps can become malignant (cancerous). This occurs when cells in these polyps begin growing abnormally. In time, malignant cells invade more and more of the colon and rectum. The cancer may also spread to nearby organs or lymph nodes or to other parts of the body. Finding and removing polyps can help prevent cancer from ever forming.
Polyps are fleshy clumps of tissue that form on the lining of the colon or rectum. Small polyps are usually benign (not cancerous). However, over time, cells in a polyp can change and become cancerous. The larger a polyp grows, the more likely this is to happen. Also, certain types of polyps known as adenomatous polyps are considered pre-‐malignant. This means that they will almost always become cancerous if they’re not removed.
Colorectal cancers usually start when polyp cells begin growing abnormally. As a cancerous tumor grows, it may involve more and more of the colon or rectum. In time, cancer can also grow beyond the colon or rectum and spread to nearby organs or to glands called lymph nodes. The cells can also travel to other parts of the body. This is known as metastasis. The earlier a cancerous tumor is removed, the better the chance of preventing its spread.
Treatment options for Colon and Rectal Cancer
Surgery is performed to remove the cancerous parts of the colon and rectum. Some surrounding tissue is removed as well, possibly including nearby lymph nodes.
Chemotherapy may be prescribed in addition to surgery. This therapy uses medications to attack cancer cells, and is considered systemic therapy because it works throughout the body. It’s usually done as an outpatient procedure. You may receive the medication in pill form or through an IV line or infusion pump (a device that slowly releases medication into your bloodstream).
Radiation therapy may be prescribed for rectal cancer. This treatment uses high-‐energy X-‐rays to kill cancer cells. It’s considered localized therapy because it targets the specific area of the body affected by the cancer. It is usually performed on an outpatient basis.