I’m Dr. Kenny Lin. I am a family physician and associate director of the Lancaster General Hospital Family Medicine Residency, and I blog at Common Sense Family Doctor.
I’m 47 years old. Two years ago, when the U.S. Preventive Services Task Force (USPSTF) followed the American Cancer Society and lowered the starting age for colorectal cancer (CRC) screening from 50 to 45, my family physician brought up screening options at a health maintenance visit. Although I had expressed some skepticism about this change when the ACS updated its screening guideline in 2018, I generally follow the USPSTF recommendations in my own clinical practice, so I dutifully selected a test that, fortunately, came out negative.
Not everyone in the primary care community, however, is on board with screening average-risk adults in their late 40s for colorectal cancer. The American Academy of Family Physicians (AAFP) published a notable dissent, arguing that the evidence from modeling studies cited by the USPSTF to support lowering the starting age was insufficient. The AAFP also expressed concern that devoting screening resources to younger adults could come at the expense of improving screening rates in older adults who are at higher risk for CRC and increase health care costs without corresponding benefit.
Now, the American College of Physicians has joined the AAFP by releasing an updated guidance statement for CRC screening that discourages screening asymptomatic, average-risk adults between the ages of 45 and 49. In addition to the uncertainty surrounding benefits of screening adults in this age range, the ACP pointed out that starting screening at age 45, compared with age 50, would increase the number of colonoscopies and colonoscopy complications. My colleagues and I recently published a systematic review estimating that for every 10,000 screening colonoscopies performed, 8 people suffer a bowel perforation and 16 to 36 have severe bleeding requiring hospitalization. One in 3 patients undergoing colonoscopies report minor adverse events such as abdominal pain, bloating, and abdominal discomfort in the first 2 weeks following the procedure.
Other aspects of the ACP guidance differ from other colorectal cancer screening guidelines. Unlike the USPSTF, which made no distinctions between various recommended screening tests, the ACP preferentially endorsed fecal immunochemical or high-sensitivity fecal occult blood testing every 2 years, colonoscopy every 10 years, or flexible sigmoidoscopy every 10 years plus a fecal immunochemical test every 2 years. That leaves out stool DNA testing, which my patients increasingly request because they have seen television or online advertisements, and newer blood tests that detect methylation sequences in circulating tumor DNA.
Perhaps most controversial is the ACP’s suggestion that it is probably reasonable for some adults to start screening later than age 50 or undergo screening at longer intervals than currently recommended (for example, colonoscopy every 15 years). Recent data support extending the interval to repeat screening colonoscopy in selected populations; a large cross-sectional study found a low prevalence of advanced adenomas and colorectal cancers in colonoscopies performed 10 or more years after an initial negative colonoscopy, particularly in women and younger patients without gastrointestinal symptoms. A prominent BMJ guideline suggests that patients need not be screened until their estimated 15-year CRC risk is greater than 3% (which most people do not reach until their 60s) and then only need a single sigmoidoscopy or colonoscopy.
Despite some departures from other guidelines, it’s worth emphasizing that the ACP guideline agrees that screening for CRC is generally worthwhile between the ages of 50 and 75 years. On that front, we in primary care have more work to do; the Centers for Disease Control and Prevention estimates that 28% of American adults older than 50 are not up-to-date on CRC screening. And despite some recent debate about the relative benefits and harms of screening colonoscopy, compared with less invasive fecal tests, gastroenterologists and family physicians can agree that the best screening test is the test that gets done.
A version of this article first appeared on Medscape.com.