What Is a Colon Polyp?

A polyp is a mass of tissue that develops on the inside wall of a hollow organ. Polyps can occur in many body locations, including the nose, ears, throat, or uterus.

The most common polyp is a colon polyp, also called a colonic polyp or a colorectal polyp. Fifteen percent to 40% of adults are estimated to have colon polyps, which are more common in older adults and men.

Colon polyps are the precursors of colorectal cancer, the second leading cause of cancer death in the United States. Because the risk of any particular polyp becoming malignant increases with size, regular screening and early removal is important.

Anatomy and Types of Colon Polyps

The colon is the largest part of the large intestine, which extends from the end of the small intestine to the rectum. It has four sections:

• The ascending colon, beginning with a saclike structure called the cecum, is located on the lower right side of the abdomen and curves left below the liver.
• The transverse colon extends across the abdomen from right to left.
• The descending colon drops down to the pelvis, where it curves under the small intestine.
• The sigmoid colon is the final S-shaped section, which connects to the rectum.

Colon polyps are abnormal growths that can develop in any part of the colon’s inner lining, but they are most often found in the rectum and on the left side of the colon. Most polyps are benign, but over time some may become cancerous.

Colon polyps are either flat (sessile) or have a stalk (pedunculated). There are five types of colon polyps, with the most common being adenomatous. The adenomatous type accounts for 70% of all colon polyps. Nearly all malignant polyps begin as adenomatous, but the process to evolve into cancer typically takes many years.

Colon Polyp Symptoms

For most people, colon polyps don’t cause symptoms, which is why screening is recommended. However, when symptoms do occur, they may include:

• Bleeding from the rectum after a bowel movement, showing up as blood on your toilet paper or underwear
• Blood in your stool, which can make stool have red streaks or look black 
• Constipation or diarrhea lasting more than a week
• Unexplained weight loss
• Fatigue, as bleeding from colon polyps can cause anemia
• Abdominal pain (rare) 

Other health problems can also cause these symptoms. However, if you do have bleeding from your rectum or blood in your stool, you should contact your healthcare provider immediately.

Causes

Risk factors for developing colon polyps include age, lifestyle, and personal and family health history:

• Over age 45
• Being overweight
• Consuming excessive alcohol 
• Smoking
• Eating fatty and processed foods and excessive red meat
• Not exercising
• Personal or family history of colon polyps or colorectal cancer
• Personal history of inflammatory bowel disease, such as ulcerative colitis or Crohn’s disease

Two genetic abnormalities significantly increase the risk for colon polyps and colorectal cancer—Lynch syndrome and classic familial adenomatous polyposis.

Lynch Syndrome

Lynch syndrome, also known as hereditary non-polyposis colorectal cancer (HNPCC) is among the most common hereditary cancer syndromes. As many as one in 300 people may be carriers of an altered gene associated with Lynch syndrome.

It is estimated that 3% to 5% of all colorectal cancer cases are caused by Lynch syndrome. Individuals with this condition are also at greater risk of developing other cancers and are more likely to be diagnosed at a young age. 

Classic Familial Adenomatous Polyposis

Classic familial adenomatous polyposis (FAP or classic FAP) is caused by a mutation in the adenomatous polyposis coli (APC) gene. Individuals with this condition have an increased lifetime risk of developing colorectal cancer or other cancers of the digestive tract.

FAP is diagnosed when a person develops more than 100 adenomatous colon polyps. The average age for polyps to develop in people with FAP is in the mid-teens, with most people with the condition developing multiple colon polyps by age 35.

It is estimated that one in 7,000 to one in 22,000 people have FAP, with less than 1% of all colorectal cancer caused by the condition. Although FAP is passed from generation to generation in a family, about 30% of people with FAP do not have a family history of the condition.

Diagnosis

The American College of Gastroenterology currently recommends that adults age 45 to 75 be screened for colon cancer. This updates previous guidelines, which recommended that screening start at age 50. The decision to be screened after age 75 should be made on an individual basis in consultation with your healthcare provider. 

People with increased risk should consult their healthcare providers as to when to start screening, which test to use, and frequency of screening. Increased risk includes:

• A personal or family history of colon polyps or colorectal cancer
• A personal history of inflammatory bowel disease
• Familial genetic abnormalities (Lynch syndrome and familial adenomatous polyposis)
• Having symptoms that may be indicative of polyps or colorectal cancer, such as rectal bleeding

Several screening tests can be used to find polyps or colorectal cancer, including stool tests, flexible sigmoidoscopy, colonoscopy, and virtual colonoscopy.

Stool Tests

These include any of the following:

• Fecal immunochemical test (FIT) uses antibodies to detect blood in the stool. Frequency: once a year.
• FIT-DNA test (also called the stool DNA test) combines the FIT with a test that detects altered DNA in the stool. For this test, you collect an entire bowel movement and send it to a lab, where it is checked for cancer cells. Frequency: every year or every three years.
• Guaiac-based fecal occult blood test (gFOBT) uses the chemical guaiac to detect blood in the stool. You are provided a test kit to collect a small amount of stool at home. You return the test kit to the healthcare provider or a lab, where the stool samples are tested for blood. Frequency: once a year.

Flexible Sigmoidoscopy

This is a thin, flexible tube that is inserted through the rectum to examine the last third of the large intestine (sigmoid colon) for polyps or cancer. Frequency: every five years, or every 10 years.

Colonoscopy

This is a procedure in which a long, thin, flexible tube is inserted through the rectum and into the colon. The tube has a camera that shows images on a screen. During the test, the healthcare provider can find and remove most polyps and some cancers.

Colonoscopy also is used as a follow-up test if anything unusual is found during one of the other screening tests. Frequency: every 10 years (for those without an increased risk of colorectal cancer).   

CT Colonography (Virtual Colonoscopy)

Computed tomography (CT) colonography, also called a virtual colonoscopy, uses radiation to create pictures of the entire colon, which are displayed on a computer screen for the healthcare provider to analyze. Frequency: every five years.

Treatment

Although virtual colonoscopy provides a view of the entire colon, colonoscopy is the only procedure that enables both visualization and removal of polyps.

The removal of polyps is performed as an outpatient procedure called a polypectomy. Various techniques are available.

Cold forceps and cold snare have been the polypectomy methods of choice for smaller polyps, and hot snare has been the method of choice for larger polyps. Polypectomy for difficult-to-remove polyps may require the use of special devices and advanced techniques.

Possible but uncommon complications of a polypectomy are bleeding or perforation of the colon. Bleeding can be immediate or delayed for several days. Perforation, which is a hole or tear in the colon, can often be repaired with clips during the procedure.

If a polyp is found, it will be removed and sent to a laboratory for evaluation. Your healthcare provider will recommend a follow-up schedule based on the number, size, and type of polyps you have, as well as your personal risk factors.

Prognosis

Once a colon polyp is completely removed, it rarely comes back. However, because at least 30% of patients develop new polyps after removal, a follow-up screening will be recommended. 

Depending on your personal health status, some healthcare providers recommend taking a daily aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs), as they may reduce the risk of new polyps forming. 

Maintaining healthy eating, exercise, and alcohol consumption habits will also help reduce your risk for developing colon polyps.

Prevention

Some risk factors, such as age and genetics can’t be changed. Lifestyle habits that increase the chances of developing colon polyps, however, can be modified to reduce risk:

• Lose extra weight and maintain a healthy weight.
• Don’t smoke.
• Limit alcohol consumption.
• Avoid fatty and processed foods and limit red meat.
• Eat at least three to five servings of fruits and vegetables daily.
• Exercise, including 150 minutes of moderate aerobic activity and two sessions of muscle strengthening weekly.

A Word From Verywell

Undergoing a screening for colon polyps isn’t a procedure anyone enjoys. However, keep in mind that colorectal cancer is the second leading cause of all cancer deaths. Routine screening saves many lives, one of which may be yours. The pros definitely outweigh the cons.