Factors associated with en-bloc resection and withdrawal rate in colorectal endoscopic submucosal dissection

Backgrounds: Although endoscopic submucosal dissection for neoplasms of colorectum in countries outside of Japan became common, outcome such as en-bloc resection and complications rates were mostly inferior to Japanese series. Moreover, withdrawal from ESD may be common for beginners. The aim is to find out factors that may be associated with en-bloc resection and withdrawal rates by analyzing result of our colorectal ESD.Methods: Parameters such as lesion location, size (> 5/< 5cm), malignancy, biopsy and preview colonoscopy by ESD operator were compared between lesions with/without en-bloc resection. Parameters analysis between ESD and withdrawal group were underwent. Results: Seventy-five patients received colorectal ESD at our unit. Sixty-seven were resected by ESD and eight withdrew. In ESD, mean lesion size: 3.4 cm (range: 1~9). Mean procedure time: 69.7 min (16~260). Mean resection velocity: 9.59 min/cm2. En-bloc rate: 86.56 % (58/67). Immediate perforation rate: 5.88 % (4/67). Delayed perforation or bleeding were both zero. In non-en-bloc group, previous biopsy rare was higher (Biopsy rate, en-bloc/not en-bloc: 19.0 %/55.6%, p= 0.03). Higher percentage of malignancy was shown in withdrawal group. (75.0% v.s. 13.4%, p< 0.001) Limitation: Single colonoscopist and small population. Conclusions: Previous biopsy and malignancy were factors associated with en-bloc resection and withdrawal of ESD, respectively. These could be overcome through training of endoscopic diagnostic ability.