March is Colorectal Cancer Awareness month.
During this month, it’s important to note that colorectal cancer remains the second-leading cause of cancer death in men and women. Only lung cancer takes more lives.
However, one of the true success stories in modern medicine is the dramatic decline in the incidence and death rates associated with colorectal cancer. These rates have declined by more than 40% from peaks in the 1980s.
The majority of this impact derives from the improved acceptance and utilization of screening tests for colorectal cancer. This has translated into both prevention of colorectal cancer and detection at earlier stages when the chances of cure are much higher.
Unfortunately, only 70% of Americans are up to date on colorectal cancer screening. That leaves a significant number of people at higher risk for this deadly disease. With that said, it is critical to discuss with your primary care provider or gastroenterologist how you can best protect yourself from developing colon cancer.
That discussion should focus on two key questions. When should I start screening for colorectal cancer? And what test is best for prevention of colorectal cancer? The answer to the first question has changed in the last year.
Although overall colorectal cancer diagnoses are down, it has actually increased for people under 50. This change has prompted a decrease in the age to start screening to 45 years and most government and commercial payors will now cover screening tests at that age.
The choice of screening tests requires a more in-depth discussion. There are multiple testing options, each with its own advantages and disadvantages. Colonoscopy remains the gold standard for colorectal cancer screening and prevention.
It is a tier-one test as recommended by the U.S. Multi-Society Task Force. Colonoscopy’s biggest advantage is that it is the only available test that can actually prevent colorectal cancer by identifying and removing precancerous polyps.
In addition, it allows biopsy of suspicious lesions or growths. Bowel preparation is the most commonly cited negative regarding colonoscopy, although most people tolerate the preparation without much difficulty.
Improvements have been made in the volume and taste of the various preparations. It remains a critical part of colonoscopy as a high-quality bowel preparation provides the best opportunity to detect polyps and cancers.
The interval for repeat colonoscopy is determined based on the findings at colonoscopy and any family history of colorectal cancer. A normal colonoscopy translates to a 10-year interval before the next colonoscopy.
Stool test for occult blood with FIT testing is the other tier-one test. This involves collection of a stool sample to be analyzed for hemoglobin which can indicate bleeding in the colon. This test has the advantage of lower cost and more convenience.
However, it must be performed on an annual basis and any positive test will require a colonoscopy. It also has a lower sensitivity for polyps and cancer when compared to colonoscopy.
Tier-two tests include multi-target stool DNA testing, CT colonography, and flexible sigmoidoscopy. These tests should be reserved for people who either refuse or have contraindications for either colonoscopy or stool FIT testing.
Multi-target stool DNA testing is available in the United States as Cologuard. This test has been aggressively marketed directly to consumers and more than 4 million people have been screened with Cologuard. However, there are very important limitations to this test.
In my experience, I have found that most patients who present for colonoscopy after a positive Cologuard test are completely unaware of these limitations. First, Cologuard has a significant risk of a false positive test. Any positive Cologuard test necessitates a follow up colonoscopy.
In up to one-third of cases, nothing is found at colonoscopy. This means that two tests were performed when one (colonoscopy) would have reached the same findings. This has important implications for cost as many insurance companies will only pay for the first screening test.
The responsibility of paying for the diagnostic colonoscopy after a positive Cologuard tests often falls on the patient. More concerning to many gastroenterologists is the false negative rate associated with Cologuard use.
Only 40% of polyps larger than 1 centimeter are detected by Cologuard. These are precisely the type of polyps that carry the highest risk for progression to cancer. Given the large number of Cologuard tests that have been performed, there are many people who have received a normal test but actually have precancerous polyps.
45 is the new 50 for colorectal cancer screening and of the available tests, only colonoscopy can prevent cancer. I encourage people who have not been screened to do so and ask the right questions to choose the screening test that is best for you.
Dr. Aaron Shiels, Rockford Gastroenterology Associates