Development and Validation of the Asia-Pacific Proximal Colon Neoplasia Risk Score

Area of Science:

• Gastroenterology
• Preventive Medicine
• Oncology

Background:

• Flexible sigmoidoscopy is a screening tool for colorectal cancer.
• Identifying patients at high risk for advanced proximal neoplasia (APN) is crucial for appropriate follow-up.
• Colonoscopy is recommended for high-risk individuals identified by flexible sigmoidoscopy.

Purpose of the Study:

• To develop and validate a scoring system to identify asymptomatic individuals at risk for APN.
• To determine risk factors associated with APN.
• To guide decisions for colonoscopy referral after flexible sigmoidoscopy screening.

Main Methods:

• A cohort of 7954 asymptomatic subjects (age 50-75) undergoing screening colonoscopy was used.
• Subjects were randomly assigned to derivation (n=5303) and validation (n=2651) cohorts.
• Risk factors including age, sex, family history, smoking, and distal colorectal findings were analyzed to create a risk score.

Main Results:

• The scoring system identified 20.5% of the validation cohort as high risk.
• The prevalence of APN was 1.9% in the average-risk group and 9.4% in the high-risk group (adjusted RR, 5.08).
• Key predictors for APN included age, smoking, family history, and distal colorectal neoplasia. The score achieved a c-statistic of 0.74.

Conclusions:

• A validated scoring system effectively identifies individuals at high risk for APN.
• Screening participants with a score of 4 or higher after flexible sigmoidoscopy should undergo colonoscopy evaluation.
• This scoring system aids in targeted colonoscopy referrals, improving the efficiency of colorectal cancer screening.