LAUSR

Background and Study Aims Varying degrees of fibrosis in colorectal endoscopic submucosal dissection (ESD) make the procedure difficult. Consensus on the predictive factors of fibrosis degree (mild or severe) has not been established. We conducted a study to identify the predictive factors and to examine the feasibility of ESD for fibrotic lesions. Patients and Methods We included 518 patients who had undergone ESD for 558 lesions from April 2012–September 2018. Patients were classified into fibrosis or no-fibrosis groups, and logistic regression analysis was performed to identify predictive factors of fibrosis. Subgroup analyses were performed for fibrosis degree. Results The total incidence of fibrosis was 21.1% (mild: 14.1%; severe: 7.1%). Although the curative resection rate (free margin: invasion depth less than 1000 μm: no lymphatic invasion, vascular involvement) was lower in the fibrosis group compared with the control (80.7% vs. 97.6%), neither the en bloc resection rate (99.1% vs. 100%) nor incidence of perforation (0.9% vs. 0.2%) differed between the two groups. Multivariate analysis revealed that a cecal location, preoperative biopsy, straddling fold, laterally spreading tumor–non-granular-pseudo-depressed (LST-NG-PD) type were predictive of mild fibrosis. The presence of a straddling fold and a protruded lesion were independent predictive factors of severe fibrosis. Conclusions We identified the predictive factors of mild and severe fibrosis. It is preferable that a more experienced physician performs ESD for the lesions with F2 fibrosis.