Test Utilization: New Guidelines Recommend Basing Routine Colorectal Cancer Screening on Risk Rather than Age

Even people who are not in diagnostics have probably heard that adults age 50 to 79 should get routine colorectal screening exams. But now that longstanding recommendation has changed. According to new guidelines from an international panel of researchers and experts that were published in The BMJ in early October, routine screening recommendations should be limited to individuals with an elevated level of risk rather than the entire age group. This represents a significant departure from current recommendations in most parts of the world.

 Colorectal Cancer Screening

One in 20 people in high-income countries get colorectal cancer during their lifetime. Actual risk is dependent on personal factors including:

• Age;
• Sex;
• Genetics; and
• Lifestyle factors, such as alcohol consumption, smoking, physical activity and diet.

Because risk increases with age, the global consensus is that people should start getting routine colorectal cancer screening once they reach a certain age. In most countries, the recommended age is 50 but in some countries it is as low as age 45. At age 50, the risk of developing bowel cancer over the next 15 years is typically 1-2%. The most common screening options are:

• Home faecal testing (FIT) every year or every two years;
• Sigmoidoscopy (examination of the lower colon); and/or
• Colonoscopy (examination of the entire colon) done at a clinic or hospital.

The New Approach

But now an international panel of researchers, clinicians and patients has, for the first time, discarded the strictly age-based approach in favor of one based on actual risk. The panel’s conclusions are part of The BMJ‘s ‘Rapid Recommendations’ initiative to produce rapid and trustworthy guidance based on new evidence to help doctors make better decisions with their patients. The panel made its determination after reviewing the evidence base, including new evidence about the long-term effects of bowel cancer screening, to evaluate the benefit-to-harm balance of screening using a “risk-based approach.” The panel took into account an individual’s cumulative risk of bowel cancer over the next 15 years, together with risk of harm from the procedure (e.g., bowel perforations or unnecessary treatment), quality of life (e.g., anxiety, burden of procedure), and a person’s values, preferences and life expectancy.

Overall, the panel wrote, there was “substantial uncertainty” regarding the 15-year benefits, burdens and harms of screening, with the most common screening methods resulting in similar colorectal cancer mortality reductions. “FIT every two years may have little or no effect on cancer incidence over 15 years, while FIT every year, sigmoidoscopy and colonoscopy may reduce cancer incidence, although for FIT the incidence reduction is small compared with sigmoidoscopy and colonoscopy,” the panel noted. Serious gastrointestinal and cardiovascular adverse events related to screening, meanwhile, were found to be rare.

The New Colorectal Screening Recommendations

 The panel’s conclusions:

• Routine testing for bowel cancer should not be recommended for healthy individuals age 50 to 79 who have a life expectancy of at least 15 years, because those individuals are at very low risk, meaning the benefits of routine screening are small, uncertain and outweighed by the potential harms;
• Routine screening should be recommended for men and women with a risk of 3% or more in the next 15 years, because this is the point at which the balance of benefits and harms tilts in favor of screening.

The panel declined to recommend any one test method over another, citing what it called convincing evidence that people’s values and preferences on whether to test and which test to undergo vary considerably.

The panel also stressed that there are still many uncertainties in terms of what is the most effective screening test or combination of tests and at what age and interval they should be used, suggesting that these issues should be the focus of future research.