Noriya Uedo, Department of Gastrointestinal Oncology, Endoscopic Training and Learning Center, Osaka Medical Center for Cancer and Cardiovascular Diseases, 1-3-3 Nakamichi, Higashinari-ku, Osaka 537-8511, Japan. Email: firstname.lastname@example.org
Aim: This study was carried out to understand the current practice and learning of endoscopic submucosal dissection (ESD) for superficial esophageal and gastric cancers in East Asian countries.
Methods: A questionnaire survey was used to investigate differences in upper gastrointestinal (GI) ESD among East Asian countries.
Results: ESD is used by many endoscopists in not only tertiary centers but also secondary care hospitals in China, Korea and Japan. By contrast, it is less used by doctors in tertiary centers in Hong Kong and Taiwan. However, the general trend appears to be the same; ESD, which is a highly advanced endoscopic technique, is being transmitted from preceptors to preceptees in tertiary centers, then from doctors in tertiary centers to experienced doctors in secondary hospitals. The speed of learning and uptake in the practice of this procedure will depend on the volume of cases. Upper GI ESD can be expected to spread at a similar rate across different districts or hospitals in East Asia because of similarities in disease prevalence. Also, endoscopists in this region can easily learn from each other by attending international conferences or visiting endoscopy units to learn the procedure.
Conclusion: Efforts to establish a standardized protocol for ESD practice and training are important, and may help endoscopists around the world develop this technique further.
Esophageal cancer is the eighth most common cancer worldwide and the sixth most common cause of death from cancer, and the highest mortality rates are found in East and Southern Africa, and in East Asia. For gastric cancer, half the world total occurs in East Asia (mainly in China); it is the second most common cause of cancer death worldwide (738 000 deaths, 9.7% of the total) and the highest mortality rates are estimated to be in East Asia (28.1/100 000 in men, 13.0/100 000 in women).1 Upper digestive tract cancers have a poor prognosis when they are diagnosed at an advanced stage,2 but if they are treated early, 5 year survival rates for superficial esophageal squamous cell carcinoma approaches 80%,3,4 whereas for early gastric cancer, it exceeds 90%.5 This has led not only to a rethink of the role of endoscopic diagnosis of early malignancy of the upper gastrointestinal (GI) tract during routine esophagogastroduodenoscopy (EGD), but also the appealing possibility of treating these lesions endoscopically.6,7
Japanese endoscopists have pioneered the field of advanced endoscopic treatment of superficial GI neoplasia. Endoscopic submucosal dissection (ESD) is a newly developed technique in Japan by which even a large tumor, or a tumor with a scar that had required surgery, can be removed endoscopically en bloc. However, the technique of ESD is complicated and requires considerable expertise, and an effective training system for ESD has not yet been established. Thus, despite the excellent treatment effect, some Western investigators have expressed difficulty with the feasibility and relatively high complication rate of ESD.8–10
The aim of this international questionnaire survey was to understand the current situation with regard to practice and learning of ESD for superficial esophageal and gastric cancers in East Asian countries.
This study was a questionnaire survey of representative doctors from leading hospitals where ESD is performed in five different countries and districts in East Asia. Questionnaires about indications for, distribution of practice and training in upper GI ESD for esophageal and gastric cancer were prepared and sent by email in mid-June 2011, and were retrieved by late July 2011. A question was written in each figure. Answers were confirmed and corrected by interview with the respondents at the Endoscopy Forum Japan 2011 on 30 July 2011.
Indications for ESD
Approximate proportions of ESD procedures carried out for each organ are shown in Figure 1. Esophageal ESD was more common in mainland China and Taiwan, where esophageal cancer is prevalent, than in other countries. Gastric ESD was more common in Korea and Japan. Colorectal ESD was the most common procedure in Hong Kong. The differences in these proportions probably depended on the different prevalence of cancer in each organ.
Esophageal ESD was indicated in patients with high-grade intraepithelial neoplasia (HGIN) or intramucosal cancer (confined to the epithelium, lamina propria and muscularis mucosae) in all countries (Fig. 2). ESD was also indicated in patients with submucosal tumor in all countries except Japan.
Gastric ESD was frequently indicated in patients with HGIN, intestinal type intramucosal carcinoma or carcinoma with slight (≤500 µm) submucosal invasion (Fig. 3). There was controversy surrounding gastric ESD for intestinal-type intramucosal carcinoma with ulceration or scar and diffuse-type intramucosal carcinoma. Although there were minor disagreements on the indications for gastric ESD, every country basically follows common criteria, and the availability of established guidelines11 and published data12 probably contributed to this.
Distribution of practice of ESD
ESD is now performed in secondary and tertiary care centers throughout China, Korea and Japan, whereas it is still confined to tertiary centers in large cities in Hong Kong and Taiwan (Fig. 4).
Endoscopists performed ESD in more than 100 hospitals in China and Japan, 51–100 in Korea, and 20 or less in Hong Kong and Taiwan (Fig. 5). The number of hospitals in which ESD is performed depends on the size of the population; thus, the reason why a large number of hospitals perform ESD in China may be because of the large population of the country. There are relatively large numbers of hospitals that perform ESD in Korea and Japan for their populations.
The number of doctors in a hospital who can perform ESD was mainly two to five (Fig. 6). In Hong Kong, there is a large hospital in which more than five endoscopists can perform ESD. Japan showed a wide range of number of endoscopists who can perform ESD, from one to 10 per hospital, and Korea had one to five endoscopists per hospital. These results indicate that, in Hong Kong and Taiwan, ESD is performed by only one or a few endoscopists in tertiary centers, whereas in Korea and Japan, ESD is performed by many endoscopists in tertiary centers and is spreading to endoscopists in middle-size secondary care hospitals.
Training for ESD
Taiwan has a training protocol that is authorized by a national endoscopic society. Even in Japan, there is no certification to perform ESD that is authorized by the Japanese Gastroenterological Endoscopy Society (Fig. 7). Generally, training steps before starting ESD included observation of and assistance with the procedure, attendance at workshops, watching DVDs, reading textbooks or articles, visiting experts at work and practice on animal models (Fig. 8).
Observation of and/or attendance at 15–50 ESD procedures were demanded, but this may depend on whether endoscopists work in a location near to the workplace of an experienced doctor in a high-volume center. A Japanese respondent emphasized the importance of visiting an expert to see actual work to learn the ESD procedure and associated issues such as preparation, sedation, monitoring, assistance from co-operators or nurses, usage of equipment and accessories, and specimen handling for pathological diagnosis. Moreover, by such visits, one can observe the entire procedure that may not be available on DVDs or at a conference presentation.
Some hospitals presented standards for stepping up their training protocol based on the difficulty of the procedure, according to tumor location or size (Fig. 9). The completion of each step was usually judged against the progress observed in a number of previous cases or by the acquired skill of the procedure, that is, en bloc resection or complication rate.
All respondents' hospitals had a registry system of their own, but a registry system that was administered by an endoscopic society was not available (Fig. 10).
Expectation to establish ESD
The expectation of establishing ESD in each country is listed in Figure 11. The factors that need to be addressed to help ESD become an established procedure consisted of importance of diagnosis (detection and staging), technical aspects [skill of adequately taking a biopsy specimen from a difficult site or skill of conventional endoscopic mucosal resection (EMR)], systematization of practice (establishment of standardized protocol for procedure and guidelines) and suggestion of outcome analysis to establish clinical evidence. Districts where ESD is spreading tended to expect technical improvement, and those where ESD had already become widespread were looking for refinement of quality of practice. Diagnosis is, of course, always important to ameliorate quality of treatment.
This questionnaire survey revealed some difference in upper GI ESD among East Asian countries. ESD is performed by many endoscopists in not only tertiary centers but also secondary care hospitals in China, Korea and Japan. By contrast, it is still relatively less used by doctors in tertiary centers in Hong Kong and Taiwan.
A European survey in 2010 reported that only 20 centers performed gastric ESD in Europe, which was mostly performed by a single endoscopist in each center at that time. Each European endoscopist had treated a mean of four cases during the previous year (mean total experience, 11 ESD).13 Our survey showed that upper GI ESD is performed in more than 50 centers in Korea and more than 100 in China and Japan. The reason why ESD has disseminated faster in East Asian countries than in Europe would be high prevalence of upper GI cancers in East Asia.1 The speed of learning and uptake in the practice of this procedure would depend on the volume of cases. Also, endoscopists in the same East Asian region can easily learn from each other by attending international conferences or visiting endoscopy units to learn the procedure. Upper GI ESD can be expected to spread at a similar rate across different districts or hospitals in East Asia because of similarities in disease prevalence.
Choi et al.14 have investigated a learning curve for gastric ESD and concluded that trainees would need to perform 20–40 procedures to be able to use the technique effectively. Gotoda et al.15 have mentioned that experience of at least 30 cases is required for a beginner to gain early proficiency in this technique. These suggestions were consistent with recommended numbers of procedure observation and attendance before starting ESD in this questionnaire survey. However, Yamamoto et al.16 investigated the actual learning curve of gastric ESD in three preceptee endoscopists and found that two of the three operators did not achieve a sufficient self-completion rate for submucosal dissection after 30 cases. Moreover, they indicated that baseline characteristics of the operators, such as graduation year, number of regular EGD or conventional EMR procedures carried out were not associated with learning speed. None of the countries except Korea and Taiwan have a training protocol that is authorized by a national endoscopic society. Even in Japan, there is no certification to perform ESD that is authorized by a national endoscopic society. To clarify the objective parameters that reflect actual trainee expertise, and to define relevant acquisition of skills is important to establish an adequate training system for ESD procedures.
The data was collected from only five respondents. However, all respondents are experienced proceduralists who perform ESD regularly and this survey may best reflect the ‘state of practice’ in each country. Another limitation in this survey is that clinical outcomes such as en bloc resection and complication rates were not evaluated. Endoscopy skill usually improves after performance of sufficient quantity of procedures. The learning curve may hence vary amongst endoscopists. Therefore, the assessment of quality and actual stage of expertise of each country may be difficult to gauge from this study. The final goal, however, should be achieving equality in quality of treatment outcomes. We thus believe a questionnaire survey regarding treatment outcomes and complications may be needed in the near future in order to understand and to correct the variation in quality of ESD practice.
In conclusion, although there was some difference of situation in upper GI ESD, the general trend appears to be the same among East Asian countries; even highly advanced endoscopic technique of ESD is being transmitted from preceptors to preceptees and tertiary to secondary care hospitals as well as other endoscopic procedures. Efforts to establish a standardized protocol for practice and training can accelerate dissemination of ESD in this region, and may help endoscopists around the world develop this technique further.