Colonoscopic screening for colorectal cancer has been suggested because sigmoidoscopy misses nearly half of persons with advanced proximal neoplasia.
In this study, researchers from the United States stratified the risk for advanced proximal neoplasia. They also identified groups with very low risk in which screening sigmoidoscopy alone might suffice.
The team assessed 1994 consecutive individuals (≥50 years of age) undergoing first-time screening colonoscopy between 1995 and 2001.
From these patients, the team developed a clinical index with 3 variables.
Points were assigned to categories of age, sex, and distal findings.
Risk for advanced proximal neoplasia was measured for each score.
The team tested the index on a further 1031 consecutive patients from the same screening program.
|3.4% of patients had advanced proximal neoplasia.|
|Annals of Internal Medicine|
Of the initial 1994 participants, 3.4% had advanced proximal neoplasia.
The researchers identified a low-risk subgroup comprising 37% of the cohort. These patients had scores of 0 or 1 and a risk of 0.68%.
In the validation group, risk for advanced proximal neoplasia in the low-risk subgroup was 0.4%.
The team determined that the application of their index detected 92% of persons with advanced proximal neoplasms.
If it was applied following screening sigmoidoscopy, they estimate it would reduce the need for colonoscopy by 40%.
The team found that the marginal benefit of colonoscopy among low-risk persons was small.
Dr Thomas Imperiale's team concluded, "This clinical index stratifies the risk for advanced proximal neoplasia and identifies a subgroup at very low risk".
"If it is validated in other cohorts or groups, the index could be used to tailor endoscopic screening for colorectal cancer".