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Up to 90% of colorectal cancers can be cured if they are found early. But once cancer spreads outside the colon, it is much harder to treat. That’s why regular colorectal cancer screenings, starting at age 45, are so important.
Together, Fred Hutch Cancer Center and UW Medicine offer a full range of screening options to reduce the risk of colorectal cancer or to find it at its earliest stage.
Schedule Your Screening
Talk to your primary care provider about colorectal cancer screening. UW Medicine Primary Care can help you get started with screening. You may be referred for a colonoscopy or a different screening test. Learn about Fred Hutch's relationship with UW Medicine.
If you need a colonoscopy, call 206.606.5342 to schedule your procedure at Fred Hutch Cancer Center – South Lake Union.
Screening Tests for Colon Cancer
Screening tests check for a condition, like cancer, in people who don’t have any signs or symptoms. There are several ways to screen for colon cancer. All of them can help detect possible signs of the disease. If your screening shows anything of concern, your health care team will recommend next steps. You may need further tests to learn more about your health.
To actually diagnose colon cancer, you will need a biopsy. This means taking a tissue sample, like a colon polyp or a small piece of a tumor, for testing. A pathologist, a physician who specializes in checking tissue samples, uses a microscope to see if the cells are cancer. Fred Hutch pathologists are experts in diagnosing colon cancers.
Colonoscopy for Colon Cancer
All colorectal screening tests give us valuable information. But colonoscopy is the gold standard. It’s the test used most often in the U.S. During a colonoscopy, a physician looks at the inside of your entire colon. They use a flexible, lighted tube with a video camera on the end.
If they find a polyp (growth), they can usually remove it at the same time and send it to a lab for testing. Most polyps aren’t cancer, but some may turn into cancer. Removing a polyp may prevent colon cancer before it starts. Colonoscopy is also used to diagnose colon cancer.
For screening, some people may have a flexible sigmoidoscopy instead. It’s like a colonoscopy, but the physician looks only at the lower part of the colon, not the entire colon.
Virtual colonoscopy (CT colonography) is another screening method. Despite the name, it’s different from a true “scope” procedure. The physician doesn’t put a camera inside your body. Instead, you have a computed tomography (CT) scan of your colon.
At-Home Screening Tests
Blood Tests for Colon Cancer
There are also blood tests to screen for colon cancer. They check a sample of your blood for signs that could mean cancer is present. But experts have not yet included these blood tests in the guidelines for first-line screening, according to the National Cancer Institute. The U.S. Preventive Services Task Force says it does not include blood tests in its screening guidelines because there’s not enough evidence for them and we have other effective methods.
Researchers at Fred Hutch are involved in studies to learn more about blood tests to screen for colon cancer and if they might one day replace the tests we use now.
Other Tests for Colon Cancer
If you were diagnosed with colon cancer before coming to Fred Hutch, your care team here may suggest more tests. We do this to fully understand your cancer and make a treatment plan that’s right for you.
We’ll review test results from your referring physician. Then, we may recommend tests such as:
- A repeat colonoscopy — if your previous procedure was not complete
- Imaging studies — such as a CT scan, positron emission tomography (PET) scan, magnetic resonance imaging (MRI) scan, endoscopic ultrasound or bone scan
- Blood tests — to check your levels of blood cells or your liver function
Your genetic make-up may have played a role in your cancer, and it might impact your treatment. All patients who come to our Colorectal Cancer Specialty Clinic have genetic testing and microsatellite instability testing. This testing can find a DNA-repair problem that leads to tumors. Some patients need further testing for a condition called Lynch syndrome that can be passed down in families. Based on the results, you and your family may benefit from Fred Hutch’s Gastrointestinal Cancer Prevention Program.
Fred Hutch Expertise in Colon Cancer Screening and Diagnosis
Fred Hutch has experts in screening for and diagnosing colon cancers. They include experienced gastroenterologists, pathologists and radiologists. If you have cancer, we have the latest technologies to find out as much about your disease as possible. That’s key to making a treatment plan that will get the best results for you.
We are making colon cancer screening easier to get through our Population Health Colorectal Cancer Screening Program. The program works to lower the burden of colon cancer, especially among people who have been disadvantaged due to factors like race, ethnicity or income. It aims to reduce barriers to getting screened or following up on abnormal results.
“We aim to help as many people as possible complete screening, to navigate them to treatment if they are diagnosed with colorectal cancer, and to do so guided by a focus on achieving health equity,” said Rachel Issaka, MD, MAS, the program’s director.
For people with higher risk of gastrointestinal cancers due to genetic changes or a family history of cancer, Fred Hutch has a special program. The Gastrointestinal Cancer Prevention Program offers risk assessment, screening and prevention tailored to you.
Yes. Even if you don’t have symptoms, screening is important. Colon cancer can develop without noticeable symptoms, especially in the early stages. Regular screening helps find issues before they become serious.
Each type of colon cancer screening has advantages and disadvantages. The most important thing is to choose one of the recommended methods and do it. If you’re trying to decide between methods, it’s a good idea to talk with your primary care provider. They can help you figure out what’s right for you.
“Colorectal cancer is common and very preventable with screening, but in some populations less than half of people who are eligible for screening actually take those tests,” said William M. Grady, MD, who is the medical director of Fred Hutch’s Gastrointestinal Cancer Prevention Program. “Getting people to be screened for cancer works best when we offer them screening options and then let them choose what works best for them.”
Here are some of the things to consider:
- Colonoscopy and sigmoidoscopy are the only methods that let your physician remove polyps or other abnormal tissue to prevent cancer or test for cancer cells.
- If you are at average risk and your results are normal, you will probably not need to repeat a colonoscopy for 10 years or a sigmoidoscopy for 5 years.
- You can do FIT, gFOBT or Cologuard tests at home.
- At-home tests need to be done more often. FIT and gFOBT need to be repeated once a year. Cologuard should be repeated every one to three years.
- You may need to make changes to your diet or medicines in the days before some tests, like colonoscopy and gFOBT.
- You need to prepare by cleaning out your colon in advance for colonoscopy, sigmoidoscopy or virtual colonoscopy, but not for FIT, gFOBT or Cologuard.
The U.S. Preventive Services Task Force recommends colorectal cancer screening for all adults starting at age 45. After age 75, the task force recommends talking with your health care team to decide if you still need to do screenings.
If you are at high risk for colon cancer, you may need to start screenings earlier than age 45 or have them more often. Several factors can increase your risk, like smoking, drinking high amounts of alcohol and eating a lot of processed foods or red meats. You’re also at higher risk if you have a family history of colorectal cancer, certain genetic changes or inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis. Learn more about colon cancer risk factors, and ask your primary care provider what screening schedule is right for you.
Researchers at Fred Hutch are looking for new, better ways to screen for colon cancer and save lives. For example:
- A Fred Hutch team found that a subtype of a microbe often found in the mouth can travel to the gut and grow within colorectal cancer tumors. Their findings could one day lead to better screening and treatment methods.
- Another group of Fred Hutch researchers has studied the gut microbiome. They focused on spotting common genetic traits shared by microbes in patients with colorectal cancer. The hope is that tests of a person’s microbiome might show if they are at higher risk for colorectal cancer before the disease arises.
- In 2024, the U.S. Food and Drug Administration approved a blood test called Shield as a screening method for people at average risk for blood cancer. The National Cancer Institute said the approval was based on findings from a study of nearly 8,000 people that involved Fred Hutch researchers.
If you have an abnormal virtual colonoscopy, FIT, gFOBT or Cologuard test, you will need to also get a colonoscopy. This is important to find out why the first test was abnormal. If you have an abnormal sigmoidoscopy, you will need a colonoscopy to look at the rest of your colon.
After an abnormal sigmoidoscopy or colonoscopy, the next steps will depend on what the biopsy finds. If your polyps or tissue samples were not cancer, you still might need a repeat colonoscopy sooner than 10 years to check again. If they were cancer, you will probably have imaging studies and blood tests to learn more, like the type of cancer, if it has spread beyond your colon and which treatments you need.