New risk score for colorectal cancer could guide selection of screening tests

According to published literature and guideline organizations, 85 percent of the population is classified as "average risk" for colorectal cancer, which accounts for 55,000 deaths per year. Yet colorectal cancer screening tests, while cost-effective, are underused and can be used inefficiently because of the current inability to more precisely tailor screening methods according to risk.

"The main question was, 'can the risk factors most frequently associated with the risks for colorectal cancer and advanced, precancerous polyps be used in combination to stratify risk for advanced neoplasia in average-risk persons'," said study lead author Thomas F. Imperiale, M.D., Regenstrief Institute investigator and professor of medicine at the IU School of Medicine.

The results of the study, "Derivation and Validation of a Scoring System to Stratify Risk for Advance Colorectal Neoplasia in Asymptomatic Adults," were published online August 11 in Annals of Internal Medicine, and will appear in the print publication's September issue.

The study was conducted with average-risk patients (i.e., no high-risk familial cancer syndromes) aged 50 to 80 years who were undergoing initial screening colonoscopy in several Midwestern endoscopy units and practices. Points for the risk assessment score were assigned based on risk factors for both colorectal cancer and advanced precancerous polyps: age, gender, family history of colorectal cancer, smoking history, and waist circumference. Participants were then separated by score into very low, low, intermediate and high risk categories. The researchers found that there indeed were fewer advanced neoplasms in the low and very low risk groups, suggesting that less invasive tests such as sigmoidoscopies or occult blood tests might be appropriate for those patients. However, those in the higher risk groups might need a colonoscopy.

"Our hope is that knowing the risk of advanced neoplasia may make colorectal screening more patient-centered with respect to choosing a screening test," Dr. Imperiale said.

The biggest challenges, he said, "Is getting to the point where providers are comfortable using the scoring system, reassuring patients at very low and low risk that non-colonoscopy based strategies may be as effective, and convincing high risk patients who do not want colonoscopy, to have one."