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.