Outcomes and Learning Curve in Endoscopic Submucosal Dissection of Rectal Neoplasms with Severe Fibrosis: Experience of a Western Center

INTRODUCTION: Endoscopic submucosal dissection (ESD) of lesions with severe submucosal fibrosis has been associated with worse outcomes, such as lower curative resection rate and higher incidence of adverse events. This study aims to investigate its true impact on rectal ESD performed in the West and to assess predictive factors of severe fibrosis. METHODS: We conducted a retrospective study including all rectal ESDs performed at our tertiary center from January 2013 to January 2021. Lesions were grouped as nonsevere fibrosis or severe fibrosis. ESD outcomes, predictors of severe fibrosis, and the learning curve were evaluated. RESULTS: ESD was performed in 195 lesions, 45 with severe fibrosis. Three resections were interrupted (one due to severe fibrosis). The presence of severe fibrosis was related to a significantly lower resection speed (16.93 mm²/min vs. 24.66 mm²/min, p = 0.007), en bloc (86.4% vs. 96.6%, p = 0.019), R0 (61.4% vs. 79.7%, p = 0.013), and curative (54.5% vs. 78.4%, p = 0.003) resection rates and a higher rate of hybrid ESD required to complete resection (13.6% vs. 2.0%, p = 0.005). No significant difference was noted regarding adverse events rate (18.2% vs. 8.1%, p = 0.09). Male sex, ulcerative colitis, pelvic radiotherapy, a lesion on the anastomotic site, previous manipulation, and deep submucosal invasion were independent predictors for severe fibrosis. En bloc resection rate improved during time (60.0% vs. 94.1%, p = 0.018). CONCLUSIONS: Severe submucosal fibrosis is an important factor related to noncurative resections and challenging rectal ESD. Factors predicting its severity are extremely important and could allow more experienced endoscopists to be assigned to more difficult cases, allowing safer procedures.