An Overview of Adenomatous Polyps

Removal of polyps during colon cancer screening may prevent cancer

Doctor holding a colonoscope preparing for a colonoscopy

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An adenomatous polyp is a neoplastic growth that can form on the lining of the colon (large intestine). These growths are quite common, comprising around 70% of all colon polyps. By age 60, roughly half of all people have one or more adenomatous polyps. Most of these growths are benign (noncancerous) and do not cause symptoms. There are numerous causes of colon polyps, among them genetics, age, ethnicity, and smoking. Because like most colon polyps adenomas are asymptomatic, they only can be diagnosed during a colonoscopy (a screening test for colon cancer). When a polyp (or polyps) are detected, it may or may not be treated with a procedure called a polypectomy depending on factors such as the size of the growth and its location. Only a 5% or fewer adenomas progress to cancer over the course of seven to 10 years.

Symptoms

Adenomatous polyps do not cause symptoms unless they progress to colon cancer. Even then there may be no sign of a problem until the cancer has advanced. This is why colon cancer screenings are so important.

Abdominal pain: Most polyps will not cause any pain until they grow large enough to cause a blockage in the colon. 

Anemia: A bleeding polyp, even if it is only causing a small amount of blood loss that isn’t visible in stool, can lead to anemia. 

A change in stool color: Stool can come in a variety of colors and may change based on diet or supplements being taken. Blood in the stool can make it appear dark or black. A change in stool color that can’t be attributed to food or medication should be checked out by a doctor. Black, tarry stool may contain blood and is a reason to see a physician.

Constipation or diarrhea: Most people experience constipation or diarrhea from time to time. However, when these symptoms last longer than a few days, they could be from a more serious cause. A large polyp can obstruct the inside of the colon and lead to either constipation or diarrhea. 

Rectal bleeding: Polyps can be a source of bleeding from the rectum. Blood that shows up on/in the stool, on the toilet paper, or alone in the toilet without stool can happen for several different reasons. A common reason for blood in the stool is hemorrhoids but it should always be investigated by a physician because there are more serious causes.

Bleeding from the rectum, without any pain, is the most common symptom of a polyp.

Causes

Adenomatous polyps can form anywhere in the large intestine. Currently, there is no known way to prevent polyps from growing altogether, although some known risk factors are modifiable and can be avoided.

Gene mutations may be responsible for some polyp formation because these mutations cause cells to divide in an unregulated way. This type of cell division can cause polyps to continue growing.

While there’s no way to pin down the specific cause of polyp formation, there are a few things that may be partly responsible for their development:

  • Age: Polyps are more common in people as they age, in particular over the age of 50 years.
  • Inflammation: Digestive diseases that cause inflammation, such as inflammatory bowel diseases (Crohn’s disease and ulcerative colitis) can contribute to the formation of polyps. 
  • Drinking alcohol: Drinking alcoholic beverages may increase the risk of developing colon cancer.
  • Ethnicity: People of African-American heritage may be at a greater risk of developing colon cancer.
  • Family history: Having a close family member who developed colon polyps or colon cancer is a risk factor for having polyps.
  • Personal history: Having adenomatous polyps in the past puts a person at increased risk of having more polyps.
  • Smoking: Smoking cigarettes may increase the risk of developing polyps.
  • Type 2 diabetes: The risk of developing colon polyps may be increased in people who are diagnosed with Type 2 diabetes and in which the disease is not well controlled.

Diagnosis

Polyps are found during various colorectal cancer screening tests. It is important for people to receive screening for colorectal cancer at regular intervals based on recommendations from a physician.

Beginning colon cancer screening is recommended for most people between the ages of 45 and 50, and at younger ages for those who have risk factors.

When polyps are found during screening, they can be removed, thereby removing their chance of growing and becoming cancerous.

Colonoscopy

During a colonoscopy, a long tube with a light and a camera on the end is used to look inside the colon and find abnormalities such as polyps. Patients prepare beforehand by using strong laxatives to remove all stool from the colon and receive sedatives during the test.

The benefit of this test is that when a polyp is found, it can be removed and the tissue sent for testing. Biopsies are also taken during a colonoscopy, which can be analyzed to see if there are any concerning characteristics of the cells in the colon.

Sigmoidoscopy

A flexible sigmoidoscopy is done by inserting a tube with a light and a camera on the end into the rectum and looking at the last section of the colon, which is the sigmoid colon.

The limitation of this test is that only the sigmoid section can be seen, which means the rest of the colon will not be visualized by the physician. Polyps further up in the colon can not be seen or removed.

This test may be done with or without prep and with or without sedation.

Stool Tests

A stool test will be used to look for signs of polyps and/or colon cancer in the stool. One such test, a fecal occult blood test, looks for blood in the stool that can not be seen with the naked eye (called occult blood) which could be coming from a bleeding polyp. A stool DNA test is one where the stool is tested for genetic material from a polyp or from colon cancer.

Virtual Colonoscopy

A virtual colonoscopy, which is also sometimes called a CT colonography, is done by using imaging to look at the colon. This test is less invasive than a conventional colonoscopy but a colon prep to clean the bowel of stool is necessary.

A thin tube is inserted approximately two inches into the rectum and a series of images are taken with a CT scanner (a large imaging machine shaped like a donut).

Treatment

When an adenomatous polyp is found, it likely will be removed in order to prevent it from growing and becoming a risk for cancer. If a polyp is found during a colonoscopy, it might be possible to remove it during this test. The removal of a polyp is called a polypectomy.

Certain polyps may be more challenging to remove, especially if they are larger, or are flat, are located behind a flap or fold, or have other characteristics that make them difficult to remove during a colonoscopy.

Polypectomy

Most polyps will be removed through a polypectomy. Special tools on the colonoscope are used during a colonoscopy to remove polyps, including a wire loop. The loop might be used to snare the polyp at its base and remove it.

Sometimes this can result in bleeding but it does not cause any pain and in most cases, the bleeding will resolve. Serious complications after a polypectomy are not common. A physician will give instructions on what to expect after a polypectomy and what symptoms prompt a follow-up.

Laparoscopic Surgery

If a polyp is too large to be removed during a colonoscopy, it might be necessary to use laparoscopic surgery to access it. This is also sometimes called “minimally invasive” surgery.

During laparoscopic surgery, small incisions are made in the abdomen (versus a large one in traditional surgery) to access the area where the polyp is located. Because the incisions are small, scarring is minimized and patients ofter recover quicker than with open surgery.

After a polyp is removed, the tissue will be sent to a pathologist for study. A pathologist will look at the tissue under a microscope. This is an important part of the process because if the polyp tissue is cancerous, there might be a need for other treatment or for follow-up tests.

Follow-Up

After an adenomatous polyp is found and removed, the next step is to discuss follow-up with the physician. Adenomatous polyps are a risk factor for cancer. How much risk will depend on a number of factors, which includes how many polyps there were, how big they were, what their characteristics were, and what the pathology report shows.

In most cases, follow-up after adenomatous polyp removal will include a recommendation for screening after a certain period. The interval will be decided by the physician, based on guidelines as well as other factors, such as individual cancer risk.

A sample follow-up screening schedule after one or more adenomatous polyps are found might be:

  • One to two small polyps: A repeat colonoscopy in five to 10 years
  • More than two small polyps or large polyps: A repeat colonoscopy in three years
  • More than 10 polyps: A repeat colonoscopy in three years
  • Large polyps with a complicated removal: A repeat colonoscopy in six months
  • Incomplete colonoscopy because of poor prep or other reasons: The physician will make a personalized recommendation

A Word From Verywell

There’s not much that can be done to avoid the formation and growth of polyps. Certain risk factors, such as age, can’t be changed, however living a healthful lifestyle might be helpful in reducing the risk of colon cancer.

A colonoscopy is considered the gold standard for colon cancer screening because not only can the entire colon be visualized, but polyps can be removed if they are found. Removing a polyp means that it can’t continue to grow and become cancerous. Adenomatous polyps are thought to be the precursor to colon cancer, so while they are slow-growing, it is important to find and remove them.

Follow-up after these types of polyps are found is also important to allow for early detection and removal of any new polyps that might occur. Most people do well after a colonoscopy with polyp removal and don’t have any complications.

Talk to a doctor if there are any concerns about the risk of polyps or colorectal cancer or if there are questions about when and how often to receive screening. Blood in the stool is never normal and is always a reason to talk to a doctor. 

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