FIT vs Colonoscopy: COLONPREV Trial- Gastroenterology | March 2026

Introduction

Colorectal cancer (CRC) screening strategies vary worldwide, with fecal immunochemical testing (FIT) widely used in population programs and colonoscopy dominating screening in the United States. The COLONPREV randomized trial previously showed that FIT-based screening was not inferior to colonoscopy for CRC incidence and mortality at 10 years, despite higher participation rates with FIT. However, colonoscopy consistently detects more premalignant lesions. This analysis explored an important clinical question: are the characteristics of precursor lesions different when detected through FIT-triggered colonoscopy versus primary screening colonoscopy?

Summary

This analysis from the COLONPREV trial compared colonoscopic findings in individuals undergoing primary screening colonoscopy with those undergoing colonoscopy after a positive FIT result. While colonoscopy detected more overall precursor lesions, individuals referred after abnormal FIT were significantly more likely to harbor advanced neoplastic lesions, including larger polyps (mean size 7.8 mm vs 5.6 mm), higher rates of villous architecture, and high-grade dysplasia. FIT-detected lesions were also more difficult to manage endoscopically, with higher rates of incomplete resection and surgical treatment. Despite these differences, lesion histology and anatomical distribution were similar between strategies. These findings suggest that FIT acts as a risk-stratification tool, enriching for clinically significant lesions among those referred for colonoscopy. Conversely, screening colonoscopy may detect and remove lesions at earlier stages, raising ongoing debate about potential overdiagnosis versus true cancer prevention. Long-term follow-up will determine whether these differences influence CRC incidence and outcomes.