Piecemeal Resection and Advanced Histology Independently Predict Local Recurrence After Colorectal Snare-based Endoscopic Resection: a Time-to-event Cohort Study

• Scientific Basis Endoscopic resection represents one of the main strategies for preventing colorectal cancer, significantly reducing the incidence and mortality associated with the disease. Snare polypectomy, with or without the use of thermal energy (cold snare or hot snare), is widely used in clinical practice due to its efficacy, applicability, and favorable safety profile.

However, despite the high initial success rate, local recurrence at the resection site remains a relevant clinical outcome, especially in larger lesions, piecemeal resections, and cases with advanced histological characteristics. The literature shows heterogeneity regarding independent predictors of recurrence, particularly when analyzed using time-to-event methodology.

Given this scenario, it becomes essential to identify clinical, endoscopic, and histopathological variables associated with local recurrence, allowing for better risk stratification and optimization of surveillance protocols.

• Objectives

Primary Objective:

To identify variables associated with local recurrence after loop colorectal polypectomy.

Secondary Objectives:

To evaluate the occurrence of metachronous adenomas; To assess the safety of the procedure through the analysis of related adverse events; To determine independent predictors of recurrence using time-to-event analysis;

• Study Design Type: Retrospective observational cohort. Analytical model: Longitudinal study with time-to-event analysis. Center: Tertiary referral center. Inclusion period: 2023 to 2025. Sample: 255 consecutive adult patients. Essential criterion: Undergoing at least one surveillance colonoscopy after initial polypectomy.
• Study Population

Inclusion criteria

Patients ≥18 years; Underwent snare colorectal polypectomy (with or without thermal energy); Availability of histopathological examination; At least one documented follow-up colonoscopy;

Exclusion criteria

Resection by non-loop-based techniques (e.g., isolated ESD); Absence of endoscopic follow-up; Incomplete clinical or histological data;

• Characterization of the Lesions

The lesions were described according to:

Size: dichotomized into

• <10 mm;
• ≥10 mm; Location: right colon, transverse colon, left colon, or rectum. Morphological classification: according to the Paris Classification.

Resection technique:

• En bloc;
• Piecemeal;

Histopathology:

• Tubular adenoma;
• Tubulovillous adenoma;
• Villous adenoma;
• Serrated lesions;
• Intramucosal carcinoma; * Advanced histology: defined as the presence of high-grade dysplasia and/or intramucosal adenocarcinoma.
• Outcomes 6.1 Primary Outcome Local recurrence, defined as endoscopic identification and histological confirmation of neoplastic tissue at the site of previous resection during surveillance colonoscopy.

6.2 Secondary Outcomes Metachronous adenoma: development of a new lesion at a site distinct from the initial resection.

Adverse events related to the procedure, including:

• Immediate bleeding;
• Delayed bleeding;
• Perforation;
• Post-polypectomy syndrome;
• Need for hospitalization;
• Need for surgical intervention;
• Data Collection

The following variables were collected:

7.1 Clinical

• Age;
• Sex;
• Comorbidities;
• Indication for colonoscopy;

7.2 Endoscopic

• Lesion size;
• Location;
• Morphology;
• Resection technique (en bloc vs. piecemeal);

7.3 Histological

• Histological type;
• Degree of dysplasia;
• Presence of intramucosal carcinoma;
• Classification as advanced histology;
• Statistical Analysis

• The study was structured as a time-to-event analysis;
• Estimation of cumulative recurrence incidence;
• Kaplan-Meier curves for recurrence-free time analysis;
• Comparison between groups using the log-rank test;
• Cox regression models to identify independent predictors of recurrence;
• Hazard Ratio (HR) calculation with 95% CI;
• Significance level: p < 0.05;
• Relevant Methodological Aspects Consecutive inclusion to reduce selection bias. Standardization of endoscopic reports. Histopathological review according to institutional criteria. Objective definition of recurrence (histological confirmation).
• Expected Impact

This study will allow:

• Identification of independent factors associated with local recurrence;
• Better definition of the role of advanced histology as a risk marker;
• Improvement of post-polypectomy surveillance intervals;
• Consolidation of safety data in a real-world practice setting;
• Contribution to the individualization of endoscopic follow-up.

Inclusion criteria

• Age ≥ 18 years at the time of polypectomy;
• Underwent snare polypectomy, with or without the use of thermal energy (cold snare or hot snare), performed during the study period (2023-2025);
• Procedure performed at a participating tertiary center, ensuring technical and record standardization;
• Availability of histopathological examination of the resected lesion, allowing for adequate histological characterization;
• Performance of at least one documented surveillance colonoscopy, with evaluation of the previous resection site;
• Adequate recording of clinical and endoscopic variables necessary for analysis (lesion size, location, resection technique, etc.);

Exclusion criteria

• Patients undergoing techniques other than loop polypectomy, such as: Endoscopic submucosal dissection (ESD), advanced mucosal resection not based on conventional loop, primary surgical resection of the lesion;
• Absence of follow-up colonoscopy, making it impossible to assess the primary outcome (local recurrence);
• Incomplete clinical, endoscopic, or histopathological data that prevent adequate classification of study variables;
• Invasive lesions beyond the mucosa (invasive cancer with deep submucosal invasion) that have been referred for immediate surgical treatment without endoscopic follow-up;
• Loss to follow-up before the first surveillance colonoscopy.