High-volume esophageal endoscopic submucosal dissection centers: a cut above the rest?

Endoscopic submucosal dissection (ESD) was first developed in Asia for en bloc resection of early gastric cancer [1]. The procedure was slow to disseminate for various reasons, including lack of training and expertise, higher risk of adverse events, and smaller percentage of patients with early gastric cancer who would be suitable candidates for ESD in Western populations [2]. As endoscopists became more comfortable with the procedure and devices, ESD started to be used for en bloc resection of superficial lesions throughout the colon and esophagus. The esophagus is an interesting frontier for ESD because there is a much larger Western population with early neoplastic lesions, and endoscopists are more accustomed to the idea of wide-area endoscopic resection and intramural endoscopy within the esophagus.

“It is premature to regard high-volume esophageal ESD centers as being a cut above the rest.”

In this issue of Endoscopy, Odagiri et al. share the results of a retrospective cohort study evaluating the association between hospital volume and the rate of perforation and other adverse events following esophageal ESD [3]. This study utilized a Japanese nationwide administrative database of claims data and discharge summaries. Over approximately a 6-year period, 12,899 esophageal ESD procedures from 699 hospitals were included in the study. The overall perforation rate was 3.3 %, the majority of which were managed conservatively, including some with endoscopic closure of the defect. Factors associated with overall high rates of adverse events were a very low hospital volume (8 procedures or less over this time frame) and female sex. The investigators identified that very high hospital volume, defined as 39 or more procedures over the 6-year period, was associated with a significantly lower rate of adverse events compared with very low case volume (odds ratio[OR] 0.31, 95 % confidence interval 0.12 – 0.81; P  = 0.016). It is important to note that there were no statistical differences in the adverse event rate between academic and nonacademic hospitals, and that a very small percentage of cases were for early esophageal adenocarcinoma, which is more commonly seen in Western countries.

This is the largest study evaluating adverse event rates with esophageal ESD, and the study confirms ESD to be a safe procedure despite its complexity. Although the results of this study may seem intuitive, it is important to critically evaluate the study design and results. Similar studies have been conducted evaluating the impact of hospital volume on mortality rates associated with esophagectomy for esophageal cancer. A recent meta-analysis demonstrated that esophagectomy at low-volume hospitals was associated with higher rates of in-hospital mortality (8.5 % vs. 2.8 %; pooled OR 0.29, P < 0.0001) and 30-day mortality (2.1 % vs. 0.7 %; pooled OR 0.31, P < 0.0001) compared with high-volume surgical units [4]. However, there is a big difference in assessing hospital volume for an outcome that relies on multidisciplinary care compared with an outcome associated with a procedure that is largely based on an individual’s performance. Morbidity and mortality associated with esophageal surgery depend on multiple teams, including the surgical, anaesthesiology, and nursing teams, as well as expertise in critical care management and radiology. Therefore, measuring hospital volume with regard to surgical morbidity and mortality outcomes reflects the institutional expertise of all of these disciplines. Conversely, assessing adverse events with esophageal ESD is mainly reflective of the operator performing the procedure and is not indicative of the expertise of a team.

Owing to study design, it was not possible to ascertain how many physicians were performing esophageal ESD at each center in the Odagiri et al. study. I would suspect that one individual performing esophageal ESD every 2 weeks would have a better safety profile than a center with four individuals performing the procedure every 2 months. Even with those limitations, why do high-volume centers have fewer adverse events? The authors suggest that these larger-volume centers may have better training programs. With any complex procedure, one will benefit from didactic lectures as well has hands-on training. It is not clear whether these high-volume centers have access to an animal laboratory or ex vivo models for training. In addition, high-volume centers may afford more opportunities for observation and preceptorship. There is certainly a learning curve with ESD, and several publications have suggested that performing 30 gastric ESD procedures leads to improved safety and efficiency [5] [6]. The learning curve for esophageal ESD may be shorter, especially if one has vast experience with gastric ESD. However, all endoscopists at very-low-volume centers (≤ 8 cases) and some low-volume centers (9 – 17 cases) over a 6-year period would still be on the learning curve for esophageal ESD and have yet to “master” the procedure. One variable that could have been measured and reported in this study is the volume of gastric ESD being performed at the same institution. Endoscopists who perform a large number of gastric ESD procedures may have a better understanding of the devices, and recognize tissue planes and how to manage intervening vessels. Finally, the high-volume centers appear to have had better patient selection, with a smaller percentage of patients having significant co-morbidities, including cardiovascular disease.

Perhaps the biggest remaining question is how the outcomes of esophageal ESD vary among these groups. The authors acknowledge that rates of en bloc resection, curative resection, and local and distant recurrence are lacking. Without knowing these clinical outcomes, it is premature to regard high-volume esophageal ESD centers as being a cut above the rest. For now, we know that high-volume centers have a better safety profile with the procedure. As a patient, I would prefer to seek a physician, not just an institution, with sufficient esophageal ESD volume, good clinical outcomes, and a favorable safety profile.

• References

• 1 Gotoda T. A large endoscopic resection by endoscopic submucosal dissection procedure for early gastric cancer. Clin Gastroenterol Hepatol 2005; 3: 71-73
• 2 Chandrasekhara V, Ginsberg GG. ESD for colorectal neoplasms: dissecting value from virtue. Gastrointest Endosc 2011; 74: 1084-1086
• 3 Odagiri H, Yasunaga H, Matsui H. et al. Hospital volume and adverse events following esophageal endoscopic submucosal dissection in Japan. Endoscopy 2017; 49: 321-326
• 4 Markar SR, Karthikesalingam A, Thrumurthy S. et al. Volume-outcome relationship in surgery for esophageal malignancy: systematic review and meta-analysis 2000-2011. J Gastrointest Surg 2012; 16: 1055-1063
• 5 Oda I, Odagaki T, Suzuki H. et al. Learning curve for endoscopic submucosal dissection of early gastric cancer based on trainee experience. Dig Endosc 2012; 24: 129-132
• 6 Kato M, Gromski M, Jung Y. et al. The learning curve for endoscopic submucosal dissection in an established experimental setting. Surg Endosc 2013; 27: 154-161