This project is dedicated to identify the patients with possible higher risk of adenoma recurrence who should have follow-up colonoscopy in yearly interval. As a result, it can lead to optimizing the of follow-up colonoscopies intervals in real-world practice.

In this project, 200 individuals (aged 18 - 75 years) with removed colorectal polyps larger than 10 mm during colonoscopy performed based on all indication (including symptoms and screening procedures) will be included. All procedures will be done with high quality endoscopes (high definition, HD).

In all polyps, the advanced imaging techniques (such as chromoendoscopy and NBI) will be used to determine parts of the polyp suspicious from high-grade dysplasia or cancer. The therapeutic method will be decided by the size and macroscopic appearance of the polyp. In case of flat, sessile polyps and LST lesions (laterally spreading tumors) EMR or ESD will be performed. Pedunculated polyp will be removed by EPE. The goal is to achieve the en-bloc resection. Pathologists (with presence of the endoscopist) will do the first step of histopathology evaluation (cutting the polyp tissue). The aim is to perform the first cut in the most advanced part of the polyp and high density cutting in this area. Standard histopathology evaluation will proceed and will be followed by initial basic molecular testing.

Subsequently, all patients will be observed by colonoscopy in one-year intervals with focus on polyp recurrence. The group of high-risk patients will be selected with at least one of these criteria: 1/ high grade dysplasia adenoma at index colonoscopy; 2/ high score of polyp heterogenity at index colonoscopy; 3/ polyps recurrence at follow-up colonoscopy.

In a high-risk patients group the extensive somatic mutations profiling will be carried out according to multitarget sequencing by NGS technologies (next generation sequencing). Same testing will be done in randomly selected patients not included in the high-risk group, which will be used as a control group for statistical evaluation.

Inclusion Criteria:

• Colorectal polyp larger than 10mm removed by colonoscopy therapeutic method (EPE, EMR, ESD)
• Signed informed consent with the study and with colonoscopy

Exclusion Criteria:

• FAP, HNPCC and other hereditary CRC syndromes probands
• Recent diagnostic, follow-up or preventive colonoscopy (FOBT-positive colonoscopy, screening colonoscopy) in ≤ 3 years
• Colonoscopy contraindication
• Severe acute inflammatory bowel disease
• Severe comorbidities; likely non-compliance of the patient