Scoring System Could Eliminate Colonoscopy for Low-Risk Individuals

A new scoring system may help to identify patients at low risk for colorectal cancer who could forego screening with colonoscopy, according to the results of a cross-sectional study.

The new system classifies risk according to the most common risk factors for colorectal neoplasia: age, sex, waist circumference, cigarette smoking, and family history of colorectal cancer.

“The ability to accurately and reliably estimate and stratify risk for colorectal cancer and advanced precancerous polyps among persons currently classified as average-risk could help guide choice among several available test options for patients and providers,” wrote Thomas F. Imperiale, MD, of Indiana University Medical Center, and colleagues in Annals of Internal Medicine.

“In the larger picture, such risk stratification and resultant tailoring within the average-risk group would make screening more efficient by targeting colonoscopy toward higher-risk persons and away from lower-risk persons, who could be effectively screened with less invasive tests, all of which are recommended by the US Preventive Services Task Force,” they wrote.

Imperiale and colleagues looked at 2,993 people age 50 to 80 years who were undergoing initial colonoscopy between December 2004 and September 2011. Each patient was assigned a risk score for advanced neoplasia based on the five factors associated with colorectal neoplasia. A score of 0 was assigned very low risk; 1 to 3, low risk; 4 to 6, intermediate risk; and greater than 6, high risk.

Among the patients, there was a 9.4% prevalence for advanced neoplasia. The risk for advanced neoplasia was 1.92% for patients assigned very low risk, 4.88% for those assigned low risk, 9.93% for intermediate risk, and 24.9% for high risk.

When the researchers looked at other screening methods, they found that sigmoidoscopy to the descending colon would have detected 51 of 70 (73%) advanced neoplasms in the low-risk groups.

The researchers then validated their scoring system in a group of 1,467 patients and found similar results, including the risk for advanced neoplasms: 1.65% for very low risk, 3.31% for low risk, 10.9% for intermediate risk, and 22.3% for high risk. Among the validation group, sigmoidoscopy would have detected 87.5% of advanced neoplasms in the low-risk groups.

“Persons at very low or low risk could be screened effectively and efficiently with strategies other than colonoscopy, including sigmoidoscopy every 5 years, fecal immunochemical testing annually, both strategies combined, or another less invasive strategy,” the researchers wrote, acknowledging that colonoscopy would still be warranted among those at high risk.

In an editorial that accompanied the article, Chyke A. Doubeni, MD, MPH, of the University of Pennsylvania’s Perelman School of Medicine, wrote that the study is strong because it “demonstrates the use of simple clinical information for prediction of colorectal neoplasia risk.”

However, Doubeni added that until the method is further validated with stronger scientific evidence, he would “not recommend such scores for choosing the type of screening test an average-risk person should have.”

“Because patients with a negative screening result have lower disease risk, low-risk persons with a negative result on a high-quality, high-sensitivity screening test may forego future screening, but the use of such an approach requires strong empirical evidence,” wrote Doubeni. “Thus, improved risk stratification of patients currently classified as average-risk remains an important scientific and policy aspiration.”