Diagnosis
Screening tests are important for finding polyps before they become cancerous. These tests also can help find colorectal cancer in its early stages, when you have a good chance of recovery.
Screening methods include:
- Colonoscopy. In this test, a small tube with a light and camera is inserted through the rectum to examine the entire colon. The tube is guided through the colon using air to distend the colon and to get a clear view. Images of the lining of the colon are shown in real time on a video screen. Polyps usually appear as bumps or slightly raised spots or patches on an otherwise smooth lining. If polyps are found, the healthcare professional may take them out right away or take tissue samples to send to a lab for analysis. There also is the possibility of finding other areas of concern in the colon that can be sampled at the time of the exam.
- Virtual colonoscopy. This test uses a CT scan to view the colon. Virtual colonoscopy calls for the same bowel preparation as a colonoscopy. If a polyp is found during the scan, you'll need a colonoscopy to have the polyp examined and removed.
- Flexible sigmoidoscopy. Like a colonoscopy, this test uses a small tube with a light and camera but examines just the last third of the colon. Most of the colon is not seen with this screening test, so some polyps and cancers may not be found. When this test is used, it is repeated more often than colonoscopy or is used along with a yearly stool-based test.
- Stool-based tests. There are a few of these tests available. One of these checks for blood in the stool and needs to be repeated every year. Another test checks for blood and tumor markers in the stool to look for colon polyps or colorectal cancer and is repeated every three years. If the results of a stool-based tests are positive, a colonoscopy is recommended soon afterward.
- Blood-based testing. There is an FDA-approved blood screen for colon cancer. It needs to be repeated every three years. If positive, a colonoscopy is recommended to check for colon cancer.
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.
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Treatment
A healthcare professional is likely to take out all polyps found during a bowel exam. Options for removal include:
- Polypectomy. During a colonoscopy, polyps can be taken out using a few techniques, a process called polypectomy. Very small polyps may be taken out with forceps. Small to medium polyps are usually taken out with a wire loop called a snare. Sometimes an electric current is applied to cut the polyp and prevent bleeding. Removing polyps prevents them from having the chance to grow into colorectal cancer.
- Minimally invasive surgery. Polyps that are too large or that can't be removed safely during colonoscopy are usually removed surgically. This is often done by placing an instrument called a laparoscope into the abdomen to remove the part of the bowel with the polyp or cancer.
- Total proctocolectomy. If you have a rare inherited syndrome, such as FAP, you may need surgery to remove your colon and rectum. This surgery can protect you from getting colorectal cancer.
Some colon polyps have the potential to become cancerous and others don't. A medical professional who studies tissue samples, called a pathologist, looks at the polyp tissue under a microscope to find out what type of polyp you have.
Follow-up care
If you have had an adenomatous polyp or a serrated lesion, you are at increased risk of colorectal cancer. The level of risk depends on the size, number and characteristics of the polyps that were taken out.
A healthcare professional is likely to recommend repeating a colonoscopy:
- In 7 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 in diameter or certain types of adenomas.
- In 6 months to one year if you had more than 10 adenomas, a very large adenoma or an adenoma that had to be taken out in pieces.
The follow-up colonoscopy schedule for serrated lesions is like that for adenomas.
Preparing for your colonoscopy
It's very important to fully clean out your colon before a colonoscopy. If stool remains in the colon and blocks the view of the colon wall, you will likely need another colonoscopy sooner than usual to make sure all polyps are found.
After good colon preparation, stool should appear as clear liquid. It may be slightly yellow or green depending on any liquids used while preparing. If you have trouble with your colon preparation or think that you have not fully cleaned out your colon, tell the health professional before beginning your colonoscopy. Some people need to take more steps to prepare for a colonoscopy.
If you take medicines that affect bleeding, such as aspirin or other medicines used for heart disease or blood clots, tell your healthcare team. Do not stop taking any medicines on your own. Your care team lets you know whether to keep taking them or pause them before your colonoscopy. The team also tells you how and when to start taking them again if needed.
Clinical trials
Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this condition.
Preparing for your appointment
You may be referred to a healthcare professional who specializes in digestive diseases, called a gastroenterologist.
What you can do
- Be aware of anything you need to do ahead of time, such as not eating solid food on the day before your appointment.
- Write down your symptoms, including any that may not seem related to the reason why you scheduled the appointment.
- Make a list of all your medicines, 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 go with you to help you remember what the health professional says.
- Write down questions to ask during the appointment.
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 cancerous?
- 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, don't hesitate to ask other questions during your appointment.
What to expect from your doctor
You'll likely be asked a few 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 having symptoms, and how bad are they?
- Do your symptoms happen all the time or do they come and go?
- Have you or has anyone in your family had colorectal cancer or colon polyps?
- Has anyone in your family had other cancers of the digestive tract, the uterus, the ovaries or the bladder?
- Do you smoke or drink? If so, how much?
Sept. 24, 2025