Acetic Acid-Indigo Carmine Chromocolonoscopy for Proximal Serrated Lesions: A Randomized, 3-Arm Colonoscopy Study

Area of Science:

• Gastroenterology
• Endoscopy
• Oncology

Background:

• Aggressive colorectal cancer (CRC) often arises from proximal serrated lesions (SLs).
• Detecting these proximal SLs during standard screening colonoscopy is challenging.
• Current recommendations like duplicate examinations or chromocolonoscopies lack robust randomized trial evidence.

Purpose of the Study:

• To evaluate the effectiveness of tandem colonoscopy using an acetic acid-indigo carmine mixture (AIM) for detecting proximal SLs.
• To compare AIM's performance against white-light imaging (WLI) and standard indigo carmine (IC) staining.

Main Methods:

• A 3-arm, multicenter randomized controlled trial involving 1,319 participants across 9 institutions.
• Patients were randomized to undergo colonoscopy with WLI, IC, or AIM.
• Primary outcomes included the SL-detection rate (SDR) during the second examination (SDR 2nd) and the SL additional rate (SAR).

Main Results:

• AIM significantly increased the proximal SL-detection rate (SDR 2nd) and additional detection rate (SAR) compared to WLI and IC.
• AIM showed a significantly higher adenoma detection rate (ADR 2nd) than WLI (24.7% vs 10.5%, P < 0.001).
• AIM was an independent factor for SAR (OR: 7.79; 95% CI: 3.76-17.08), with no major adverse events reported.

Conclusions:

• Tandem colonoscopy with AIM is superior to WLI and IC for detecting proximal serrated lesions.
• The improved detection of SLs and adenomas using AIM warrants further investigation into its impact on CRC incidence.