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Colorectal cancer screening

Colorectal cancer (CRC) is a cancer of the colon (large intestine) and rectum (the last part of the large intestine). Currently, it is the fourth most common cancer in the United States. It is also the second leading cause of cancer-related death.1 Fortunately, CRC is one of the most preventable cancers.Healthcare providers use screening to find or prevent CRC. Screening identifies people who have, or might get, a disease. Unfortunately, in the United States about 1 in 3 people who should be screened for CRC have not been screened.2

How CRC Develops

CRC usually begins in the colon as abnormal tissue growths called polyps. When a polyp first begins to grow, it is generally not cancerous. But if the polyp continues to grow it may become a cancer. This change usually takes 10 or more years.3 So if you are screened for CRC, your healthcare provider usually has plenty of time to find and remove a polyp before it becomes cancer.

Who Is at Risk for CRC?

Everyone is at risk. Men and women of all racial and ethnic groups can get CRC. However, some people are at increased risk. These people include those who drink a lot of alcohol, smoke, don’t exercise, and are overweight or eat too much food high in unhealthy fats and low in fiber.1 But age is the biggest risk factor: CRC is most frequently diagnosed among people aged 65-74.CRC is more common in some families than others. That’s because CRC may be caused by a change in a gene, called a mutation. Cancer caused by a mutation passed down from a parent is called hereditary cancer. If one of your parents or a brother or sister had CRC, you are more likely to get it.1 Lynch syndrome and familial polyposis are examples of conditions caused by hereditary cancer. Family members that have these conditions are at higher risk for CRC.5 To see if you’re at risk for developing hereditary cancer, you can take this online quiz and share the results with your healthcare provider.

When You Should Begin Screening

In 2018, the ACS changed the recommended age to begin screening for CRC from 50 years old to 45 years old.1 The change was because more younger adults are getting CRC and dying because of the disease. The recommended age of 45 years is for people with an average risk of developing CRC. People should be screened at an even younger age if they are at higher risk of CRC because it runs in the family.

Symptoms of Colorectal Cancer

Screening for CRC is important because symptoms may not be noticeable, especially early on. Some common symptoms are6

  • Blood in your stool—the blood can be red, or cause your stool to be very dark
  • A change in bowel habits, such as diarrhea, constipation, or narrowing of the stool, that lasts for more than a few days
  • Unintended weight loss
  • Persistent cramping or abdominal pain

Screening Options

Colonoscopy is the main screening method for CRC. Healthcare providers use colonoscopy to look inside your colon to find CRC and precancerous polyps that can be removed. To perform a colonoscopy, your physician uses a flexible endoscope to look at the inside of your colon while you are under sedation. Stool-based laboratory screening methods involve checking stool for traces of blood. As polyps grow, they can bleed, and the blood mixes with the stool. Usually the amount is too small to be seen. This is called occult blood. Stool tests help your healthcare provider find occult blood in the stool. There are 2 methods:

  • One method is called guaiac-based. The drawback is that many different foods can cause a positive result even though there is no blood. You may be advised to be on a special diet for 2 or 3 days before the test.
  • The other stool-based method is called a fecal immunochemical test—FIT for short. This test is very accurate and the results are not affected by what you eat. So you do not have to be on a special diet.

For people with an average risk of CRC, a colonoscopy is recommended every 10 years.1 For people who do not want to have a colonoscopy, a stool-based test is recommended every year.1 Blood in the stool can be a sign of CRC, but not always. It can also be caused by other conditions such as hemorrhoids and diverticulitis. Discuss your results with your healthcare provider. If you have blood in your stool, they may recommend that you have a colonoscopy.

How Your Healthcare Provider Can Help

Your healthcare provider can help you determine the best screening method for you, and how often you should be screened. He or she can also answer any questions you may have about screening. Make sure you tell your healthcare provider if you have any symptoms suggestive of CRC. Importantly, make sure that you give your healthcare provider your complete medical and family history so they can work out whether you’re at average or increased risk for CRC.

How the Laboratory Can Help

Quest Diagnostics offers a stool screening test that is simple to do at home and does not require you to handle stool. The test only needs to be performed once a year if your risk for developing CRC is average. The InSure® ONE™ FIT only requires that you gently brush the surface of the stool in the toilet with the supplied brush after a bowel movement. You then dab the brush on the test card and mail the card to the lab. Ask your healthcare provider if the InSure ONE FIT is the right test for you.

Additional Information on CRC

For more information, visit Quest Diagnostics, or these helpful websites:



  1. Wolf AMD, Fontham ETH, Church TR, et al. Colorectal cancer screening for average-risk adults: 2018 guideline update from the American Cancer Society. CA Cancer J Clin. 2018;68:250-281.
  2. Use of colorectal cancer screening tests by state. Centers for Disease Control and Prevention website. Updated July 23, 2019. Accessed April 6, 2020.
  3. Recio-Boiles A, Cagir B. Cancer, Colon. StatPearls. Treasure Island, FL: StatPearls Publishing; 2017. Updated June 3, 2019. Accessed April 6, 2020.
  4. Cancer stat facts: colorectal cancer. National Cancer Institute: Surveillance, Epidemiology, and End Results Program website. Accessed April 6, 2020.
  5. Rex DK, Boland CR, Dominitz JA, et al. Colorectal cancer screening: recommendations for physicians and patients from the U.S. Multi-Society Task Force on colorectal cancer. Gastroenterology. 2017;153:307-323.
  6. Colorectal cancer signs and symptoms. American Cancer Society website. Updated February 21, 2018. Accessed April 6, 2020.