The term colon polyp refers to an abnormal growth in the lining of your colon. There are many different types of polyps, but it's thought that only about 10 percent of them ever grow into colon cancer. These growths can be categorized as benign (non-cancerous), pre-cancerous or cancerous.
How Polyps Increase Your Colon Cancer Risk
Getting diagnosed with colon polyps does not necessarily mean anything special – 1/3 of Americans over the age of 50 have them. However, certain types of polyps can grow, mutate and become cancerous, and this is thought to occur over slowly, over a period of 10 to 20 years. The slow growth rate of the polyp is the main reason that colon cancer has a high rate of preventability. If your doctor finds the right kinds of polyps – i.e. the ones that may grow into cancer – he or she can remove them before they have a chance to mutate further.
How You Get Polyps
You can get polyps in a number of different ways. As you age, polyps can grow in your colon, which is why you should begin screening tests for colon cancer around the age of 50 years old. Some people will grow polyps sooner, due to a lifestyle and diet that facilitate polyp growth, or you may have a hereditary syndrome, such as familial adenomatous polyposis (FAP), which is a rare genetic condition that stimulates the growth of pre-cancerous polyps in your colon.
Decreasing Your Risk
The majority of adults over 50 will have polyps in their colon, but you can decrease the risk factors that attribute to polyp growth and reduce your risk of developing colon cancer. The factors you can control include:
- Quit smoking: the risk of developing polyps is two to three-times higher if you smoke
- Clean up your diet: a diet high in fat, red meat, and low in fiber may increase your risk of colon cancer
- Drinking alcohol to excess increases your risk of colorectal cancers
- Get moving: people who are physically active have less risk of developing cancers of the colon and rectum
- Lose weight if necessary, as obesity increases your risk for cancer
There are risk factors that you cannot control, which include your gender, age, bowel diseases and family history. A history of inflammatory bowel disease, type 2 diabetes, or familial conditions that increase your risk of developing polyps, such as the familial adenomatous polyposis syndrome (FAP) or hereditary nonpolyposis colorectal cancer syndrome (HNPCC), also put you at increased risk.
If you have a first-degree family member (brother, sister, father, mother, child) with colon cancer or polyps, your risk for developing colon cancer is increased. In your case, the guidelines to begin colorectal cancer screening tests at the age of 50 do not apply – your doctor may want to start screening much sooner.
Familial Adenomatous Polyposis Syndrome (FAP) is a family-inherited syndrome that causes the development of hundreds (even thousands) of pre-cancerous polyps in your colon. Although it is fairly rare, people with FAP can be diagnosed with colon cancer as early as their teens. FAP symptoms may include changes in bowel habits, abdominal pain or bloody stools (from large polyps).
Hereditary Nonpolyposis Colorectal Cancer Syndrome (HNPCC), also referred to as Lynch syndrome, is a family-inherited condition that may increase your risk of developing colon cancer by as much as 80 percent. There are no outward symptoms of HNPCC, but genetic testing, a family history of colon cancer and screening exams, such as a colonoscopy, will help your doctor diagnose this syndrome.
Peutz-Jeghers Syndrome(PJS) is an inherited condition that causes colon polyps that are more prone to becoming cancerous. PJS is not common, affecting between one and 25,000 to one and 300,000 people at birth. PJS can be passed on to a child (50/50 chance of that) or developed sporadically (uknown cause). Some symptoms associated with the syndrome, which are usually spotted at birth, include pigmented dark spotting on the lips or in the mouth, clubbing of the finger or toenails, and blood in the stool.
Symptoms of Polyps
For the most part, polyps will sit and grow quietly in your colon without any outward symptoms. A large polyp may bleed, which may be seen in the stool or on a fecal occult blood test. Less commonly, you may suffer fatigue, which can occur with excess blood loss (bleeding in the colon from very large or cancerous polyps).
Types of Polyps
Polyps are named according to their location, type and appearance. You can develop polyps in any portion of your colon or rectum. The most common type of polyp is the tubular polyp, which is also the least likely to become cancerous.
Most commonly, cancers of the colon develop from adenomatous polyps, with adenocarcinoma being the most prevalent type of colorectal tumor. Adenomatous polyps can be villous (frond or leaf-like), raised or flat.
Hyperplastic polyps are less frequently associated with colon cancer, however they can be pre-cancerous if found on the right side of your colon or if you have a familial history of genetic syndromes (FAP, HNPCC).
Testing for Polyps
There are many different screening tests used to detect the presence of polyps in your colon. The majority of these exams require a bowel preparation to empty the colon of stool and liquid contents, allowing clear visualization of polyps.
- Colonoscopy – used to visualize and remove large polyps
- Virtual Colonoscopy (CT Colonography) – used to visualize polyps
- Double-Contrast Barium Enema (DCBE) – used to visualize polyps
- Fecal Occult Blood Test (FOBT) – used to detect bleeding in the stool
Once a polyp has been identified, the doctor will assess its type and size, and may choose to remove it and decrease the risk of that polyp becoming cancerous in the future. The removal of a polyp is called a polypectomy, which is usually completed during your colonoscopy or sigmoidoscopy.
If your doctor finds innumerable or very large polyps, he or she may talk to you about surgically removing a portion of your colon, which is called a colectomy.
Risks of Polyp Removal
Like any medical procedure, there are risks associated with polyp removal including the risk of bowel perforation (a hole in the bowel), bleeding and infection, to name a few. Be sure to discuss the risks and benefits of polyp removal with your doctor.
American Cancer Society. (2006). American Cancer Society’s Complete Guide to Colorectal Cancer. Clifton Fields, NE: American Cancer Society.
Medline Plus. (n.d.). Peutz-Jeghers Syndrome. Accessed January 25, 2012.
National Cancer Institute. (n.d.). Colorectal Cancer Prevention (PDQ). Accessed January 22, 2012.
National Digestive Diseases Information Clearinghouse. (n.d.). What I Need to Know About Colon Polyps. Accessed January 21, 2012.