This study aims to explore the risk factors associated with the development of ACN and same-site ACN in patients with SP, thereby informing the optimization of clinical surveillance strategies

Inclusion Criteria:

• Adult patients aged > 18 years;At least one SP detected during the index colonoscopy and pathologically confirmed as TSA or SSL (according to the 2019 WHO classification criteria);Underwent complete polypectomy during the index colonoscopy;Received regular follow-up at Changhai Hospital, with an interval of ≥ 6 months between the index and follow-up colonoscopies;Complete clinical and pathological data.

Exclusion Criteria:

• Incomplete colonoscopy or failed cecal intubation;Inadequate bowel preparation, defined as a Boston Bowel Preparation Scale (BBPS) score < 6 or a score < 2 in any bowel segment;Withdrawal time < 6 minutes;Diagnosis of hereditary cancer syndromes, such as familial adenomatous polyposis (FAP) or Lynch syndrome;Concurrent inflammatory bowel disease (IBD) or indeterminate colitis;History of colorectal cancer or other malignancies;Incomplete clinical or pathological records.

Patients who underwent at least two surveillance colonoscopies at the Digestive Endoscopy Center of Shanghai Changhai Hospital between 2000 and 2025 were enrolled as study participants