In a recent article, we covered findings that recommendations for people to take a daily aspirin for primary prevention of cardiovascular and cerebrovascular may be causing more harm than good, causing experts to question the validity of this advice. This isn’t the first time longstanding health advice has been cast into doubt by more recent research. For example, low-sodium diets may not be as beneficial as they’re purported to be, elevated LDL cholesterol may not play a significant role in cardiovascular disease risk, and contrary to long-held belief, high protein intakes are not harmful for bone health or kidney function in most people. The most recent subject to find itself on the chopping block is routine screening for bowel cancer in patients age 50-79. Let’s take a closer look at this.
The Division of Cancer Prevention and Control of the US Centers for Disease Control and Prevention (CDC) currently recommends that colorectal cancer screening begin for individuals soon after age 50, but suggests starting earlier for individuals with a family history of this or who are living with an inflammatory bowel disease such as Crohn’s disease or colitis. However, research published last month in BMJ suggests this may not be necessary for all patients.
Taking into account risk factors indicating cumulative risk of bowel cancer over the next 15 years, along with potential for harm from the procedure (such as a bowel perforation or unnecessary treatment), plus quality of life factors (anxiety, burden of procedure), and a patient’s preferences and values, researchers arrived at a recommendation for no screening for adults age 50-79 who have a life expectancy of at least 15 years, who show no signs or symptoms of colorectal cancer, who have not been screened in the past, and whose estimated 15-year bowel cancer risk is below 3%. For individuals with a risk 3% or greater, however, they suggest screening with one of four screening options: annual or biennial fecal immunochemical test (FIT), a single sigmoidoscopy, or a single colonoscopy. Additionally, the recommendation for no screening at age 50-79 does not apply to individuals who have been screened previously, have a history of colon polyps or colorectal cancer, have an inflammatory bowel disease, or who have genetic factors that increase risk for this type of cancer.
Researchers do not recommend one type of screening over another, rather, they take practical considerations into account and make allowances for patient preferences. (Here’s a helpful illustration of the many different concerns with regard to the different screening methods.) Evaluation via FIT, for example, is much more straightforward and convenient than a sigmoidoscopy or colonoscopy. It’s non-invasive and doesn’t require uncomfortable preparation or adjustment in medications as may be required before the more invasive test methods. These factors are important because it doesn’t matter how effective or reliable a test is if patients don’t want to do it. (Just like a diet—it’s irrelevant how effective a certain dietary approach is if a patient simply won’t follow it.)
Findings suggested that the different screening methods had nearly identical effects on prevention of death from colorectal cancer, but sigmoidoscopy and colonoscopy appeared to confer a small benefit with regard to cancer incidence.
It should be noted that the researchers acknowledge the strength of their findings is weak: “Overall there was substantial uncertainty (low certainty evidence) regarding the 15-year benefits, burdens and harms of screening.” It’s heartening to see an assessment of the quality and strength of evidence included here. Lack of certainty, unreliable data, weak findings, and overstatement of results are black marks that tarnish health and nutrition research.
It’s important to identify which kind of testing is appropriate for which patient populations, not just for colorectal cancer, but for any health concern. Over-testing and over-screening can be financially burdensome on individual patients and federal healthcare funding overall. The increased costs, however, may pale in comparison to the emotional turmoil of receiving a false positive result, and even more so in comparison to injury that may occur during testing procedures.