When Should You Begin Colon Cancer Screenings?

Colonoscopy is considered the gold standard for colon cancer screenings. Not only can it find cancer early, it often prevents cancer from occurring in the first place by finding and removing polyps before they become cancerous – a transition that can take 10 or more years.

Because colon cancer often appears without symptoms until quite advanced, screenings are essential to find and stop the disease early when it is treatable and beatable.

“Polyps are fairly common,” gastroenterologist Gregory Cooper, MD says. “About 30 percent of the population has them. Some of them develop into cancer. But when we remove them during colonoscopy, we can prevent cancer from developing.”

Even though many people dread the prep, Dr. Cooper reminds us, “It’s a small inconvenience for a potentially life-saving test.”

When to Get Screened

In 2019 the American Cancer Society updated its colorectal cancer screening guidelines, which have been adopted by the UH Digestive Health Institute, that colorectal cancer screening should begin at age 45 for all people at average risk. Previous guidelines said screening should start at 50 years of age and at age 45 in African-Americans.

Colon cancer can occur at any age, but it more common in older adults, so merely being older than 50 will usually put you in the average risk category. Talk to your doctor about your medical and family history to determine your risk level.

Men and women at an increased or high risk of colorectal cancer may need to start colon cancer screenings earlier and/or be screened more often. These conditions make your risk higher than average:

• A personal history of colorectal cancer or adenomatous (noncancerous) polyps
• A personal history of inflammatory bowel disease (ulcerative colitis or Crohn’s disease)
• A strong family history of colorectal cancer or polyps
• A known family history of a hereditary colorectal cancer syndrome such as familial adenomatous polyposis (FAP) or Lynch syndrome (hereditary non-polyposis colon cancer or HNPCC)

Individuals with any of these colon cancer risk factors may be advised to begin screening procedures at age 40, or even younger. If you have a first degree relative (parent, sibling or child) who was diagnosed with colon cancer, your first colonoscopy may be recommended when you are age 40 or 10 years younger than your family member was at diagnosis, whichever is earlier – for example, if your mother was diagnosed at 45, you may be advised to begin screenings at age 35.

Screening Frequency

The time between colonoscopies will depend on your risk factors and what is found during your initial screening.

If you are at average risk and your colonoscopy reveals no abnormal findings, it is likely you won’t need another screening for 10 years. If there are findings, or if you fall into one of the high-risk categories, your doctor will explain your results and decide when you should next be screened, which is usually every five years.

What Happens During a Colonoscopy?

During a colonoscopy, your gastroenterologist uses a scope to look at the inside of your colon for polyps or evidence of cancer. Your doctor will talk with you about sedation options to make the procedure as comfortable as possible.

If polyps are found, they are removed during the exam and sent to a lab for further examination.

The exam takes about 30 minutes to complete, and requires a full colon cleansing on the day before the test. The colon prep is considered to be the most difficult part of the procedure, but your doctor can give you some helpful tips to make the prep easier.

Alternatives to Colonoscopy

Other tests are available to look for colon cancer but colonoscopy is considered the most effective way to find, treat and prevent the disease. Other methods include:

• Fecal immunochemical testing (FIT). This involves collecting a small sample of stool to check for the presence of blood, which could be a sign of colon cancer. It is relatively easy to do but needs to be done on a yearly basis to be most effective. Because a positive FIT does not indicate what the source of blood is, a colonoscopy is needed to evaluate positive tests.
• Stool DNA testing. This involves collecting a whole stool sample which is then mailed to a central laboratory and can detect DNA mutations that are seen in colon cancer and large polyps. It is relatively easy to do and is recommended to be performed every 3 years. If the test is positive, a colonoscopy is required to evaluate further.
• Virtual colonoscopy. Also known as CT colonography, this screening test uses x-ray technology to examine the colon. It also requires the complete colon prep.

Related links

A colonoscopy screening can not only catch colon cancer early – when it is most treatable – but a colonoscopy can also stop colon cancer before it develops by finding and removing pre-cancerous polyps. Learn more about colonoscopy at University Hospitals.