Merck Manual

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Commentary— Do I Really Need a Colonoscopy? What Patients Need to Know About Screening for Colorectal Cancer

Commentary
12/16/19 Minhhuyen Nguyen, MD, Fox Chase Cancer Center, Temple University;

In terms of things people eagerly anticipate, a colonoscopy is pretty near the bottom of the list. In fact, more than seven out of 10 Americans say they would avoid or delay getting a colonoscopy for one reason or another, according to a recent survey by the Merck Manuals. About a third said they’d avoid it because the preparation process is unpleasant, while others say they’re too embarrassed or are afraid it will be painful. While it may never be something people look forward to, a lot of the apprehension people feel is based on an outdated understanding of what a colonoscopy entails.

A colonoscopy today is much different than it was 20 years ago. And the benefits of the preventive screening far outweigh any unpleasantness that comes with the exam or preparing for it. Outside of skin cancers, colorectal cancer is the third most common cancer among men and women in the U.S. Preventive screenings like colonoscopy are the best way to catch colon cancer early so it can be effectively treated.

Easing anxiety about colonoscopies starts with eliminating uncertainty. Here are six questions to ask your doctor when it comes to the procedure and effective preventive care.

1. What is a Colonoscopy?

A colonoscopy is a screening test for colon cancer that involves inserting a flexible viewing instrument into the large intestine to detect polyps. Often, polyps discovered during the colonoscopy are removed during the procedure and evaluated for possible cancer.

The colon must be thoroughly cleaned for the procedure, which requires specific preparation ahead of time. This preparation involves drinking a laxative and going to the bathroom multiple times until your colon is cleansed.

2. At What Age Should I Get a Colonoscopy?

Screening for colorectal cancer (CRC) should begin at age 50 for people who are at average risk of developing colorectal cancer. However, individuals may want to talk to their doctor sooner. The American Cancer Society recommends individuals of average risk begin colorectal cancer screenings at age 45. The group made this shift in 2018 in response to rising rates of colorectal cancer among individuals under 50. Many other groups, including the U.S. Preventive Services Task Force, still recommend individuals with average risk begin screening at age 50.

There’s no benefit to waiting. At a minimum, people with average risk of colorectal cancer should have a conversation with their doctor about screenings by their 45th birthday.

Screening for colorectal cancer should continue until age 75. For adults aged 76 to 85, doctors take into consideration the person's overall health and the results of previous screenings to decide whether to continue screening.

 3. What are the Colon Cancer Risk Factors?

What does “average risk” for colon cancer mean? There’s no set definition, but there are important risk factors to be aware of. The most significant factor is a family history of colon cancer. Individuals who have a first-degree relative (a parent, sibling, or child) who has had colorectal cancer may need to begin screenings earlier. Other risk factors include having colon diseases like ulcerative colitis and Crohn disease

It's important to note that colorectal cancer grows slowly and does not cause symptoms for a long time. Yet more than a third of those surveyed by Merck Manuals who would delay having a colonoscopy said they would wait because they didn’t have any concerning symptoms. Individuals should be screened based on their risk factors and age, not whether or not they are experiencing symptoms like fatigue or bleeding during a bowel movement.

 4. How can You Make the Preparation a Little Easier?

There’s no getting around it. The prep for a coloscopy involves drinking a good amount of liquid and going to the bathroom many times. But it’s less unpleasant than it once was. These days, the most common preparation includes drinking three to four liters of liquid and using the bathroom many times in the 24 hours leading up to the procedure. You’ll also need to avoid solid foods and drink only clear fluids during that period.  

The specifics of the preparation process will vary depending on your situation and your doctor’s preferred methods. Talk to your doctor about the details of the prep, including how quickly to drink the liquids. Follow up with any questions you have in the days leading up to the procedure. 

5. Can I be Sedated?

Most people having a colonoscopy choose to be sedated. Yet nine percent of individuals say they’d delay getting a colonoscopy because they don’t want to be sedated. In most cases, people can choose not to receive moderate anesthesia if they are concerned about the slight risks of sedation and the required recovery time.

6. What other screening options are there?

Other screening options include the fecal immunochemical test (FIT), which looks for blood in the stool and is conducted annually, and the fecal DNA test, which looks in stool for genetic material from a cancer. Genetic stool tests are often combined with fecal immunochemical tests for blood (FIT-DNA tests) and done every 3 years. These tests can be done at home, and the results are available quickly. If these stool tests are positive, people then need to get a colonoscopy. People should talk to their doctor about whether or not these stool tests are good screening options for them.

Remember: Age is just a number. Each individual’s risk and best approach to screening will be slightly different. The best place to start is talking with your doctor – the earlier the better. Refer to the Manuals page on colorectal cancer to prepare for that conversation.

Minhhuyen Nguyen, MD

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