Transanal endomicrosurgery in the treatment of large and giant rectal adenomas. Results of a prospective study

AIM: the aim of this article was to demonstrate the possibilities of using TEM for large (more than 5.0 cm) and giant (more than 8.0 cm) rectal adenomas.PATIENTS AND METHODS: more than 1000 transanal endoscopic microsurgery procedures were performed in 2011- 2023. Three groups were distinguished according to the tumor size: Group I — tumors less than 5.0 cm; Group II — tumors 5.0–8.0 cm (large); Group III — tumors more than 8.0 cm (giant).RESULTS: the final analysis included 600 patients. Group I with sizes less than 5.0 cm included 465 (77.5%) patients. Group II — large adenomas 5.0–8.0 cm included 120 (20%) patients. The group of giant tumors, larger than 8.0 cm, included 15 (2.5%) patients. In group I (less than 5.0 cm), the R0 rate was 92%, then in group II of large adenomas (5.0–8.0 cm) it was only 75%, and in the case of removal of giant adenomas (more than 8.0 cm) — 46% (p < 0.001). In multivariate analysis, independent risk factors for R1 resection were giant tumor size over 8.0 cm (OR 5.5; 95% CI: 1.4–20.3; p = 0.006) and tumor site close to the dentate line (OR 2.6; CI: 1.17–5.89; p = 0.0005).CONCLUSION: giant size (over 8.0 cm) and adenoma site in the low rectum close to the dentate line are independent risk factors for non-radical resection during transanal endomicrosurgery.