The Association between Distal Findings and Proximal Colorectal Neoplasia: A Systematic Review and Meta-Analysis

Area of Science:

• Gastroenterology
• Preventive Medicine
• Endoscopy

Background:

• Flexible sigmoidoscopy (FS) screening detects distal hyperplastic polyps (HPs).
• The necessity of subsequent colonoscopy for patients with distal HPs is debated.
• Evaluating the link between distal findings and proximal neoplasia (PN) is crucial for screening guidelines.

Purpose of the Study:

• To assess the association between distal hyperplastic polyps (HPs) and proximal neoplasia (PN) or advanced proximal neoplasia (APN).
• To inform clinical decisions regarding colonoscopy referral after FS detecting distal HPs in asymptomatic, average-risk individuals.

Main Methods:

• Systematic review and random-effects meta-analysis of 28 screening studies (104,961 subjects).
• Searched Ovid Medline, EMBASE, and Cochrane Library up to June 2016.
• Extracted and pooled data on distal findings and PN/APN, including odds ratios (ORs) and confidence intervals (CIs).

Main Results:

• Distal hyperplastic polyps (HPs) were not associated with proximal neoplasia (PN) (OR=1.16) or advanced proximal neoplasia (APN) (OR=1.09) compared to normal distal findings.
• Distal adenomas, however, were associated with higher odds of PN/APN.
• The association between distal and proximal findings was weaker in higher-quality studies with larger sample sizes and robust quality control.

Conclusions:

• Distal hyperplastic polyps (HPs) alone, detected by flexible sigmoidoscopy (FS), are not predictive of proximal neoplasia (PN) or advanced proximal neoplasia (APN).
• Routine colonoscopy referral solely based on distal HP detection may not be warranted for all screening participants.
• Individual risk factors for proximal neoplasia should guide colonoscopy referral decisions.