Colon Polyps & Colon Cancer Risk

colon polyp removal
Eraxion/iStockphoto

The term colon polyp refers to an abnormal growth in the lining of the 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.

Getting diagnosed with colon polyps does not necessarily mean anything—one third of Americans over the age of 50 have them.

However, certain types of polyps can grow, mutate, and become cancerous. This is thought to occur slowly, over a period of 10 to 20 years.

The slow growth rate of the polyp is the main reason that colon cancer is very preventable. If your doctor finds the right kinds of polyps—the ones that may grow into cancer—he or she can remove them before they have a chance to mutate further.

Risk Factors

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 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.

Genetics

If you have a first-degree family member (brother, sister, father, mother, child) with colon cancer or polyps, your risk of 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)

This 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, this 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)

This 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 (unknown cause). Some symptoms associated with the syndrome, which is 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.

Decreasing Risk

The majority of adults over 50 will have polyps in their colon, but can decrease the risk factors that contribute to growth and reduce the risk of developing colon cancer.

Such controllable factors 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 and red meat and low in fiber may increase risk of colon cancer.
  • Drink alcohol in moderation—Excess alcohol consumption increases risk of colorectal cancers.
  • Exercise—People who are physically active have less risk of developing cancers of the colon and rectum.
  • Lose weight (if necessary)—Obesity increases risk for cancer.

It is important to note that there are risk factors that you cannot control, which include gender, age, bowel disease, and family history.

A history of inflammatory bowel disease, type 2 diabetes, or familial conditions that increase risk of developing polyps, like FAP or HNPCC, can also put you at increased risk.

Symptoms

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 experience fatigue, which can occur with excess blood loss (bleeding in the colon from very large or cancerous polyps).

Diagnostic Testing

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. Such tests include:

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.

Treatment

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.

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.

Also, if your doctor finds innumerable or very large polyps, he or she may talk to you about surgically removing a portion of your colon. This is called a colectomy.

Sources:

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. 

National Cancer Institute. (n.d.). Colorectal Cancer Prevention (PDQ).

National Digestive Diseases Information Clearinghouse. (n.d.). What I Need to Know About Colon Polyps. 

Continue Reading