Risk index for colorectal cancer may improve screening value, study finds
It may be possible to effectively screen those at very low or low risk with strategies other than colonoscopy, such as sigmoidoscopy every 5 years, annual fecal immunochemical testing, both strategies combined, or another less invasive strategy.
New research suggests that risk stratification may help determine which patient groups would benefit from either colonoscopy or noncolonoscopy cancer screening strategies.
Researchers created a point-based risk index for advanced neoplasia anywhere in the colorectum using common risk factors: age, sex, waist circumference, cigarette smoking, and family history of colorectal cancer. Results of the cross-sectional study were published online on Aug. 11 by Annals of Internal Medicine.
The study examined “average-risk” patients age 50 to 80 years undergoing initial screening colonoscopy from December 2004 to September 2011 in the Midwest. The cohort was split into derivation and validation sets according to strata of advanced adenoma detection, sex, family history, and body mass index.
Among 2,993 participants in the derivation set, rates of advanced neoplasia for those identified by the index as very low, low, intermediate, and high risk were 1.92% (95% CI, 0.63% to 4.43%), 4.88% (95% CI, 3.79% to 6.18%), 9.93% (95% CI, 8.09% to 12.0%), and 24.9% (95% CI, 21.1% to 29.1%), respectively (P<0.001). Sigmoidoscopy to the descending colon in the low-risk groups would have detected 51 of 70 (73% [95% CI, 61% to 83%]) advanced neoplasms, according to the study.
In the 1,467-person validation set, risks for advanced neoplasia were 1.65% (95% CI, 0.20% to 5.84%), 3.31% (95% CI, 2.08% to 4.97%), 10.9% (95% CI, 8.26% to 14.1%), and 22.3% (95% CI, 16.9% to 28.5%), in each risk group, respectively (P<0.001). Sigmoidoscopy would have detected 21 of 24 (87.5% [95% CI, 68% to 97%]) advanced neoplasms, according to the study.
The researchers concluded that those at very low or low risk could be effectively screened with strategies other than colonoscopy, such as sigmoidoscopy every 5 years, annual fecal immunochemical testing, both strategies combined, or another less invasive strategy. For patients at high risk, screening with colonoscopy seems to be warranted, and those at intermediate risk could choose from the available tests, according to the study.
The study authors noted limitations of the study, such as how 94% of people in the convenience sample were white and how results apply only to first-time screening. “If this [risk] index is further validated externally in independent cohorts, it could increase the uptake and efficiency of colorectal cancer screening in the United States,” they wrote.
A sensitive algorithm may have a role in guiding follow-up after a negative screening result, but until more research is completed, the most viable approach is for clinicians to give patients the best test they are willing and able to complete, according to an accompanying editorial. “The [risk] score may be useful in counseling average-risk patients about their risk for colorectal cancer,” the editorialist wrote. “But until stronger scientific evidence is available, I would not recommend such scores for choosing the type of screening test an average-risk person should have.”