Diagnosis

Screening tests play a key role in detecting polyps before they become cancerous. These tests can also help find colorectal cancer in its early stages, when you have a good chance of recovery.

Screening methods include:

  • Colonoscopy, the most sensitive test for colorectal polyps and cancer. If polyps are found, your doctor may remove them immediately or take tissue samples (biopsies) for analysis.
  • Virtual colonoscopy (CT colonography), a minimally invasive test that uses a CT scan to view your colon. Virtual colonoscopy requires the same bowel preparation as a colonoscopy. If a polyp is found during the CT scan, you'll need to repeat the bowel preparation for a colonoscopy to have the polyp examined and removed.
  • Flexible sigmoidoscopy, in which a slender tube with a light and camera is inserted into your rectum to examine the last third of your colon (sigmoid) and rectum. The majority of the colon is not examined with this screening test, so some polyps and cancers may not be discovered.
  • Stool-based tests. This type of test works by checking for the presence of blood in the stool or assessing your stool DNA for evidence of a colon polyp or cancer. If your stool test is positive you will need a colonoscopy soon afterward.

Mayo Clinic Minute: What you need to know about polyps in your colon

"Generally speaking, we encourage all adults over the age of 50 – and even older adults who have at least 10 years of very high-quality life expectancy – to participate in screening," Dr. Kisiel says.

He says you might be surprised how often colonoscopies uncover polyps lurking in your colon.

"Precancerous polyps are extremely common," he says. "We expect to find them in more than a quarter of the colonoscopies that we do at a minimum. So, you know, maybe a third or even a half of all patients getting [a] colonoscopy will have precancerous polyps."

Although 1 in 20 Americans will be diagnosed with colorectal cancer in his or her lifetime, Dr. Kisiel says having polyps does not necessarily mean you will get cancer.

"Of all the polyps that we see, only a minority will turn into cancer," he says. "Sometimes they just go away on their own, but removing polyps is thought to be one of the mechanisms by which we can prevent the formation of cancer in the first place."

That's why regular screening is so important.

The downside is that if a polyp is found in your colon, you may have to get screened more frequently. But that's certainly better than having to go through treatment for colorectal cancer.

Treatment

Your doctor is likely to remove all polyps discovered during a bowel examination. The options for removal include:

  • Removal with forceps or a wire loop (polypectomy). If a polyp is too large to remove with this method, a liquid may be injected under it to lift and isolate the polyp from surrounding tissue so that it can be removed.
  • Minimally invasive surgery. Polyps that are too large or that can't be removed safely during screening are usually removed surgically, which is often performed by inserting an instrument called a laparoscope into the abdomen to remove the diseased portion of the bowel.
  • Colon and rectum removal (total proctocolectomy). If you have a rare inherited syndrome, such as FAP, you may need surgery to remove your colon and rectum to protect you from developing a life-threatening cancer.

Some types of colon polyps are more likely to become cancerous than others. A doctor who specializes in analyzing tissue samples (pathologist) will examine your polyp tissue under a microscope to determine whether it is potentially cancerous.

Follow-up care

If you have had an adenomatous polyp or a serrated polyp, you are at increased risk of colon cancer. The level of risk depends on the size, number and characteristics of the adenomatous polyps that were removed.

You'll need follow-up screenings for polyps. Your doctor is likely to recommend a colonoscopy:

  • In 5 to 10 years if you had only one or two small adenomas
  • In 3 to 5 years if you had three or four adenomas
  • In three years if you had 5 to 10 adenomas, adenomas larger than 10 millimeters, or certain types of adenomas
  • Within six months if you had multiple adenomas, a very large adenoma or an adenoma that had to be removed in pieces

Preparing for your colonoscopy

It's very important to fully prepare (clean out) your colon before a colonoscopy. If stool remains in the colon and obstructs your doctor's view of the colon wall, you will likely need a follow-up colonoscopy sooner than usual to ensure that all polyps are discovered.

After a good colon preparation, bowel movements should appear as clear liquid, which may be slightly yellow or green-tinged, depending on the color of any liquids consumed during the preparation. If you experience trouble with your colon preparation, or feel that you have not been cleaned out by the preparation, you should discuss this with your doctor before beginning your colonoscopy, as some people require additional steps in preparation before attempting colonoscopy.

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Preparing for your appointment

You may be referred to a doctor who specializes in digestive diseases (gastroenterologist).

What you can do

  • Be aware of any pre-appointment restrictions, such as not eating solid food on the day before your appointment.
  • Write down your symptoms, including any that may seem unrelated to the reason why you scheduled the appointment.
  • Make a list of all your medications, vitamins and supplements.
  • Write down your key medical information, including other conditions.
  • Write down key personal information, including any recent changes or stressors in your life.
  • Ask a relative or friend to accompany you to help you remember what the doctor says.
  • Write down questions to ask your doctor.

Questions to ask your doctor

  • What's the most likely cause of my symptoms?
  • What kinds of tests do I need? Do these tests require any special preparation?
  • What treatments are available?
  • What are the chances these polyps are malignant?
  • Is it possible that I have a genetic condition leading to colon polyps?
  • What kind of follow-up testing do I need?
  • Should I remove or add any foods to my diet?
  • I have other health conditions. How can I best manage these conditions together?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask other questions during your appointment.

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may leave time to go over points you want to spend more time on. You may be asked:

  • When did you first begin experiencing symptoms, and how severe are they?
  • Have your symptoms been continuous or occasional?
  • Have you or has anyone in your family had colon cancer or colon polyps?
  • Has anyone in your family had other cancers of the digestive tract, the uterus, ovaries or the bladder?
  • How much do you smoke and drink?

Colon polyps care at Mayo Clinic

July 20, 2021
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