You should do it—it’s good for you. We constantly receive messages like this. Sometimes these messages are grounded in evidence and concern over our well-being (quit smoking, exercise, wear a seatbelt) and sometimes not (use my proprietary colon detoxifier). The recommendation to undergo colorectal cancer (CRC) screening unquestionably belongs in the first group. Screening for CRC is proven to decrease the risk of disease-specific morbidity and mortality, it can probably extend life expectancy,1 and it should be relatively easy: it is not a daily commitment, like taking lipid-lowering medication; it does not deny a pleasure, like giving up smoking or certain foods; it does not demand sustained vigorous effort, like an exercise program. So, problem solved.
Except that we all know it’s not. Screening for CRC is a case study on fundamental ethical questions and social challenges: autonomy vs paternalism, informed decision-making, individual responsibility, choice, reason vs emotion, shared risk, delayed benefit. We cannot force people to undergo a preventive health intervention that might benefit them and has a very small but nonzero chance of hurting them. So, what should we do at the population level?
Mehta et al2 grapple with this question in their provocative randomized clinical trial of CRC screening with 3 arms: no choice over screening modality (colonoscopy only), active choice (colonoscopy vs fecal immunochemical test [FIT]), and sequential choice (colonoscopy first and FIT choice for initial nonresponders). The authors report CRC screening completion rates at 4 months of 14.4% (95% CI, 8.7%-20.1%) in the colonoscopy-only arm, 17.1% (95% CI, 11.0%-23.2%) in the sequential choice arm, and 19.9% (95% CI, 13.4%-26.4%) in the active choice arm, with no statistically significant differences between arms. Classic barriers cannot explain the relatively low short-term participation rates; almost all patients had insurance and did not have low household income.
In interpreting their results, Mehta et al2 note the lack of statistically significant differences in screening rates between arms and emphasize that framing of choice influenced the selection of screening modality. I view the primary outcome differently. The results show a non–statistically significant trend toward a higher screening rate with active choice, followed by sequential choice, followed by the colonoscopy-only option. The differences between arms were, in fact, statistically significant for women. The sample size was too small to detect statistically significant differences of approximately 5% in absolute screening rates. The authors speculate that participants might have experienced choice overload. While I agree that choice overload is possible in CRC screening (the list of all guideline-endorsed screening options3 can be overwhelming), I think most people can handle a choice between colonoscopy and FIT. This study’s primary result is not inconsistent with previous research suggesting that choice leads to higher screening participation rates.4-6
What to make of the relatively low screening participation rates? Achieving participation in CRC screening can be a years-long project. Countless patients have told me that their physicians or families have been asking them to undergo screening for years. Adherence increases with age. Approximately 56% of individuals aged 50 to 64 years and 72% of those aged 65 to 75 years in the United States undergo CRC screening.7 Although Mehta et al2 do not report the study participants’ CRC screening history, it is likely that most were previously unscreened. Study patients were in their 50s and 60s; they had not just reached screening eligibility. Individuals who had already embraced colonoscopy or who adhered with programmatic FIT would have been excluded, leaving a more screening-refractory group. The short-term screening rates in the study must be viewed in this context.
What is necessary for a truly informed decision about CRC screening? Humans rarely make decisions based on quantitative analysis.8 Our gut reactions integrate emotions, thoughts, and data, but our weighing of probabilities and the value of outcomes is far from a coldly logical, mathematical exercise. Those inclined to think quantitatively might want to know some basic data. For example, lifetime risk of CRC in the United States is approximately 4% to 5%, but many in the population already undergo screening, so lifetime risk without screening may be 7% to 8%. Depending on modality, current screening options may decrease CRC incidence by as much as 50% to 75% and decrease CRC-specific mortality by more; this probably results in reduced overall risk of premature mortality, but that effect can apply to no more than 1% to 2% of all people with average risk. Screening requires some inconvenience (eg, bowel preparation or handling of stool) and incurs some risk (overall <1 in 1000 risk of serious colonoscopy-related complications). How can the typical patient digest this? And it does not yet touch on choosing a screening modality. Some might settle for a much simpler, qualitative summary, and some might prefer to ask their trusted physicians what to do.
In the study by Mehta et al,2 participants received a letter from their primary care physicians describing the benefits of CRC screening. What information was presented, how was it presented, and specifically how were numbers handled? In short, how informed would a careful letter reader be after reading the letter? Beyond this, how many of us have casually thrown out an unsolicited letter after only a glance or no glance at all?
I agree with Mehta et al2 that, regarding the 3 interventions, the format of choice is crucial. I would go further and point out the obvious: exactly what people are told, and how, could really matter. It is not clear to me, for instance, if study participants appreciated the difference between one-time vs programmatic testing. A program of annual FIT and a program of screening colonoscopies every 10 years may yield comparable benefits,9 but how many of those electing FIT understood that FIT is recommended annually? Very few of us are psychologists, survey experts, or behavioral economists, but we can all look at the exact text of the outreach messages in each study arm, which appear in the Supplement to the article by Mehta et al,2 and ask: how would I react to these messages? Can I imagine ways in which outreach might capture my attention better or move me to action more effectively? If this were easy, we would have long ago solved this problem.
Because the devil is in the details, a key question regarding all studies like the one by Mehta et al2 is about generalizability. Which patients were studied? What exactly was the intervention? What information did patients have? What support did the system provide? When we allow ourselves to pull away from our focus on CRC screening and we survey an individual’s entire health landscape—and beyond that, their entire life landscape—the complexities can feel overwhelming. Almost nobody wakes up in the morning thinking that today is the day they’ll schedule their CRC screening. How do we build systems so CRC screening fits in a person’s life?
As we endeavor to craft programs that realize the promise of CRC screening,10 the study by Mehta et al2 reminds us of key principles: limited choice is probably good; outreach and a system can make a big difference; CRC screening is a long-term project; different interventions may be needed in different populations and health systems; and, when it comes to any intervention, the devil is in the details.
Many screening-eligible persons remain unscreened. The challenge continues.
Published: August 30, 2019. doi:10.1001/jamanetworkopen.2019.10452
Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2019 Ladabaum U. JAMA Network Open.
Corresponding Author: Uri Ladabaum, MD, MS, Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University School of Medicine, 430 Broadway St, Pavilion C, Third Floor, C-326, Redwood City, CA 94063-6341 (firstname.lastname@example.org).
Conflict of Interest Disclosures: Dr Ladabaum reports receiving personal fees for consulting from Clinical Genomics, Covidien, Motus GI Holdings, and Quorum Health and receiving equity for serving on the advisory boards of Universal Diagnostics and Lean Medical.
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Ladabaum U. You Should Get Screened for Colon Cancer, Really. JAMA Netw Open. 2019;2(8):e1910452. doi:https://doi.org/10.1001/jamanetworkopen.2019.10452
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