The American Cancer Society recently released important new data showing that the rate at which people are diagnosed with colon cancer in the U.S. has dropped 30% in the last ten years for those aged 50 and older.  Much of this decline was attributed to the widespread uptake of colonoscopy screening.  Colonoscopy is the only screening test that examines the entire colon and allows removal of precancerous polyps in the same procedure.  Other tests can be used for screening, but if any of those tests is positive the next step will be a colonoscopy.

According to a recent study published in the New England Journal of Medicine, a patient’s risk of developing colon cancer depends partly on how skilled the doctor is at detecting and removing a type of precancerous polyp called an adenoma.

What can patients do to continue this positive trend, while maximizing the effectiveness and safety of their colonoscopy?

Patients can play a more active role in ensuring a safe, high-quality colonoscopy.  First, patients should feel comfortable asking about the experience and competency of the person who will perform their procedure.  One important question to ask is, “What is your adenoma detection rate?” The adenoma detection rate (ADR) is the percentage of patients age 50 or older in whom the doctor found one or more precancerous polyps (adenomas) during a screening colonoscopy. The gastroenterology community has established minimum thresholds for ADR. Doctors should find one or more adenomas in at least 25 percent of their male patients and in at least 15 percent of their female patients.  More and more, we are focusing on and measuring ADR because it is considered the most important indicator of quality colonoscopy.

In some cases, a patient might not meet the gastroenterologist prior to a screening colonoscopy. Therefore, patients can ask about the gastroenterologist’s ADR when they call to schedule the procedure. It’s likely the person scheduling the colonoscopy will not have that information, but someone should be able to call you back later.

A comprehensive list of questions to ask your physician before a colonoscopy is provided by the American Society for Gastrointestinal Endoscopy.

Another important way patients can ensure high quality colonoscopy is through effective bowel preparation.  This refers to the laxatives taken beforehand to clean the colon of fecal debris.  Patients often say that the examination itself was easy, but that the bowel preparation was challenging. Bowel preparation, however, is one of the most important things a patient can do to ensure a successful colonoscopy.

Doctors performing the procedure need to have the clearest possible view of the colon lining to maximize the chance of finding precancerous lesions.  Many of these lesions have a flat shape and may be quite subtle in appearance, so that a suboptimal bowel preparation can prevent their detection.  Several studies have shown that when bowel cleansing is impaired, fewer polyps are found.  It’s now clear that the bowel cleansing is better when patients take at least half of the preparation regimen on the day of the procedure.  This approach is called “split-dosing” or “same-day dosing” and differs from the old approach, which was to take all of the preparation the evening before colonoscopy.

Do not be surprised if you receive instructions to take half or more of the regimen on the day of the procedure.  And if you have an early morning procedure, this could mean getting up in the night to take part of the regimen. It’s worth it!  If you have a poor bowel preparation, your examination will last longer as the doctor tries to clear out debris and optimize the view. If the bowel preparation is too poor to be corrected, you’ll be asked to return for another colonoscopy sooner than would otherwise be needed, which could increase your costs and will expose you to added inconvenience. Patients should read the bowel preparation instructions well in advance of the procedure, call the endoscopy center if they have questions, and follow the written instructions carefully.

We know that colon cancer screening contributes to lives saved. Patients have an important role to play in that process: 1) Age is the single most important risk factor for colorectal cancer.  If you are 50 or older, or have a family history of colon cancer, talk with your doctor about getting screened, 2) seek out a qualified doctor with a proven high rate of adenoma detection to perform your screening, 3) follow your physician’s instructions for bowel preparation carefully, and 4) return for follow-up exams as recommended.

The American College of Gastroenterology (ACG), American Gastroenterological Association (AGA) and American Society for Gastrointestinal Endoscopy (ASGE) — the gastroenterology societies — have come together on an important initiative to highlight the value of colonoscopy and the gastroenterologists that perform this life-saving procedure.

Douglas K. Rex is a gastroenterologist and member, governing board, American Society for Gastrointestinal Endoscopy.