Risk of Metachronous Advanced Colorectal Neoplastic Among Individuals With Varying Numbers of Non-Advanced Adenomas Detected During Screening Colonoscopy

Colorectal cancer (CRC) is the third most commonly diagnosed malignancy worldwide and the second leading cause of cancer-related mortality. In recent years, with increasing westernization of diet and lifestyle, both the incidence and prevalence of CRC in China have risen sharply. CRC has become the most common gastrointestinal malignancy in the country, ranking second in incidence and fifth in mortality among all cancers. Screening colonoscopy and appropriate surveillance intervals can substantially reduce CRC-related deaths.

The latest 2020 U.S. Multi-Society Task Force (USMSTF) guidelines classify patients with 1-2 non-advanced adenomas (NAAs), 3-4 NAAs, and >4 NAAs as having low-, intermediate-, and high-risk colonoscopic findings, respectively, and recommend surveillance intervals of 7-10 years, 3-5 years, and 3 years for these groups. However, accumulating evidence suggests that the risk of developing metachronous advanced colorectal neoplastic lesions (ACRN) in individuals with 3-4 NAAs may be comparable to those with only 1-2 NAAs, raising concerns regarding the appropriateness of current surveillance recommendations.

Using a real-world, endoscopy database, this study systematically evaluates the association between different NAA counts and the subsequent risk of ACRN, providing evidence to inform optimization of post-polypectomy surveillance intervals.

Inclusion criteria

• First-time screening colonoscopy
• Only non-advanced adenomas (no villous features, no high-grade dysplasia, and diameter <10 mm) were detected during first-time screening colonoscopy
• Individuals with at least one surveillance colonoscopy
• Complete electronic medical record and pathology information

Exclusion criteria

• Inadequate bowel preparation (BBPS < 6)
• Emergency colonoscopy
• History of colorectal cancer
• Incomplete pathology information or incompletely resected polyps
• Screening colonoscopies performed by endoscopists with a low dynamic adenoma detection rate (ADR < 15%)
• Follow-up duration < 6 months