What Is High-Risk Colon Cancer Screening?

In 2018, the American Cancer Society lowered the threshold for individuals to undergo colon cancer screening from age 50 to 45. Since then, other authoritative organizations have adopted these guidelines as well, such as The U.S. Preventive Services Task Force (USPSTF). While all patients should schedule their colon cancer screenings at age 45, those with higher risk factors for colon cancer should be screened earlier for the disease. 

Early detection is key for colon cancer, and it is the third leading cause of cancer death in the United States. This is in part because colon cancer in the early stages rarely has symptoms, so by the time it is discovered, the colon cancer has spread to the lymph nodes or vital organs in the later stages. In these later stages, survival rates drop considerably. 

What Makes a Person High Risk for Colon Cancer?

There are several factors that can indicate a person is at high risk for developing colon cancer. Some of the factors are behavioral and preventable, while others are out of a patient’s control. 

It’s imperative you know your family history, so you can let your primary care physician or your gastroenterologist know if there is a history of colorectal cancer (cancer of the colon, rectum, or both) or polyps. Also, immediate family members with gastrointestinal conditions, such as inflammatory bowel disease (IBD), may place you in a higher-risk category. Additionally, a personal history of colon cancer or polyps puts you at high risk. Other high-risk factors include:

• A personal history of IBD (such as ulcerative colitis or Crohn’s disease)
• A history of radiation to the pelvic area
• A family history of hereditary colorectal cancer syndromes; these include Lynch syndrome and familial adenomatous polyposis (FAP), among others

If you meet any of these criteria, you should let your physician know, especially if you are under 45 and have not yet had a colon cancer screening. 

What Are the Different Types of Colon Cancer Screening?

There are several different types of colon cancer screening for average and high-risk patients. The preferred gold standard of colon cancer screening is colonoscopy. During a colonoscopy, your physician will insert a long, thin, and flexible tube with a small camera attached to your anus. A colonoscopy allows the doctor to see the entire colon (also known as the large intestine. Also, if benign or cancerous polyps are present, they can be removed during the procedure. 

A flexible sigmoidoscopy can also screen for colon cancer. It is very similar to a colonoscopy, particularly when it comes to prep and clearing out the colon. Still, the sigmoidoscope does not give your healthcare provider a view of the entire colon, just part of it. 

Before your doctor orders invasive diagnostic tests, they may opt for other tests first. While a colonoscopy or sigmoidoscopy are extremely accurate, there are other colon cancer screenings as well. They include:

• Stool-based testing. For this test, you will provide the laboratory with a stool sample. This is a diagnostic test—it looks for blood in the stool or abnormal DNA. Any positive stool test requires a colonoscopy for a complete evaluation. Blood in the stools is not just indicative of colon cancer as it can be found in several other gastrointestinal disorders. So there are often instances where such tests do not yield any signs of colon cancer when one undergoes a follow-up colonoscopy for a positive test.
• Virtual colonoscopy. For a virtual colonoscopy, you will empty your large intestine, as with a regular colonoscopy. Instead of inserting a tube, your doctor will use computerized tomography (CT) scan to view your colon. One drawback of this test is that a virtual colonoscopy cannot remove any polyps if they’re detected. If polyps are present, you will have to schedule a colonoscopy.
• Double-contrast barium enema. An enema containing contrast (barium) is inserted into the colon using an enema. After the barium is present in the colon, your doctor will use X-rays to get a closer look at your large intestine. 

If I Am High Risk, When Should I Be Screened?

The American Cancer Society does not offer screening guidelines for high-risk patients, however, the American College of Gastroenterology (ACG) does have some advice for patients of high risk. 

If you have an immediate family history of colorectal cancer, the ACG recommends that you have a colon cancer screening at age 40 or 10 years before the youngest affected relative, whichever comes first. For example, if a relative with colon cancer developed it at age 45, you should be screened at age 35. Generally speaking, the ACG recommends that higher-risk patients have colonoscopies every five years (as opposed to 10 years for those of average risk). 

The ACG also suggests genetic testing to see if you are at higher risk for colon cancer. Any type of cancer in the immediate family can raise your risk, and genetic testing can let you know if you have genetic mutations, such as the ones associated with Lynch syndrome or familial adenomatous polyposis. Genetic testing can search for these and other genetic mutations, which can place you at higher risk.