Endoscopic submucosal dissection for colorectal laterally spreading tumors: Clinical outcomes and predictors of technical difficulty

Tumor size discrepancy between endoscopic and pathological evaluations in colorectal endoscopic submucosal dissection

BACKGROUND

Tumor size impacts the technical difficulty and histological curability of colorectal endoscopic submucosal dissection (ESD); however, the preoperative evaluation of tumor size is often different from histological assessment. Analyzing influential factors on failure to obtain an accurate tumor size evaluation could help prepare optimal conditions for safer and more reliable ESD.

AIM

To investigate the tumor size discrepancy between endoscopic and pathological evaluations and the influencing factors.

METHODS

This was a retrospective study conducted at a single institution. A total of 377 lesions removed by colorectal ESD at our hospital between April 2018 and March 2022 were collected. We first assessed the difference in size with an absolute percentage of the scaling discrepancy. Subsequently, we compared the clinicopathological characteristics of the correct scaling group (> -33% and < 33%) with that of the incorrect scaling group (< -33% or > 33%), which was further subdivided into the underscaling group (-33% or less of the discrepancy) and overscaling group (33% or more of the discrepancy), respectively. As secondary outcome measures, parameters on size estimation were compared between the underscaling and correct scaling groups, as well as between the overscaling and correct scaling groups. Finally, multivariate analysis was performed in terms of the following relevant parameters on size estimation: Pathological size, location, and possible influential factors (P < 0.1) in the univariate analysis.

RESULTS

The mean of absolute percentage in the scaling discordance was 21%, and 91 lesions were considered to be incorrectly estimated in size. The incorrect scaling was significantly remarkable in larger lesions (40 mm vs 28 mm; P < 0.001) and less experience (P < 0.001), and these two factors were influential on the underscaling (75 lesions; P < 0.001). Conversely, compared with the correct scaling group, 16 lesions in the overscaling group were significantly small (20 mm vs 28 mm; P < 0.001), and the small lesion size was influential on the overscaling (P = 0.002).

CONCLUSION

Lesions indicated for colorectal ESD tended to be underestimated in large tumors, but overestimated in small ones. This discrepancy appears worth understanding for optimal procedural preparation.

Effectiveness of water pressure method in colorectal endoscopic submucosal dissection by novice endoscopists

Background and study aims Colorectal endoscopic submucosal dissection (ESD) remains challenging for novice endoscopists. Not only the underwater conditions but also active use of water pressure with the water pressure method (WPM) can help widen the submucosal layer. This study aimed to clarify the usefulness of WPM in colorectal ESD, especially for novice endoscopists. Methods This study was ex vivo and enrolled three novices. Each endoscopist performed conventional ESD (C-ESD) and ESD with WPM (WPM-ESD) 10 times on an excised bovine rectum. The treatment outcomes were compared between the two groups. Results Median procedure time was significantly shorter in the WPM-ESD group than in the C-ESD group (54 minutes, interquartile range [IQR] 42-67 vs. 45 minutes, IQR 34-55, P  = 0.035). Although no significant difference in the activation time of electrical surgical unit (ESU) during the procedure was noted, the interval time during the procedure at which the ESU was not activated was significantly shorter in the WPM-ESD group (52 minutes, IQR 40-65 vs. 42 minutes, IQR 32-52, P  = 0.030) than in the C-ESD group. Moreover, the time required for the endoscope to enter the submucosa was significantly shorter in the WPM-ESD group than in the C-ESD group (8.0 minutes, IQR 6.0-10 vs. 5.0 minutes, IQR 3.0-6.0, P  < 0.001). Conclusions The present study reveals that the WPM method significantly shortens the procedure times for novices in colorectal ESD, especially the interval time, which refers to the time spent creating the field of view, and the time required for the endoscope to enter the submucosa.