Thank you chairman for your nice introduction. It¡¯s a great honor for me to talk in this prestigious meeting today. 
Topics of my presentation will include various issues of ESD. 
I¡¯d like to start with history of gastric ESD in Korea. 
This is the first small clinical report on endoscopic treatment of early gastric cancer in Korea in 1996. Professor Á¤Çöä performed all the procedures, and I was the first author of that report. At that time, I was a senior resident at Seoul National University Hospital. 
This is one of my early experiences of gastric ESDs in 2005. I used paper medical records and polaroid films at that time. 
This is a national statistics. For about 3 years, 23 thousands ESDs for EGC was done. In the year 2014, it was 7,734. The mean age of patients were 65 years and male was 74%. Mean duration of hospital stay was 5 days. Mean medical cost in 2014 was 1,305 US dollars. Surgery was done in 6.6% within 3 months. 
This is the volume of surgery and ESD at my institution. More than 35% of gastric cancer patients are initially treated by ESD in the year 2018.
Next topic is indications.
Before further discussion, I¡¯d like to make the definitions clear. Indications are different from criteria. Indication is something that we consider before the treatment. Criteria is something we consider after the treatment. Decision about additional surgery is made by the criteria.  
There are two types of indications. Absolute indication means differentiated type mucosal cancer without ulcer and not bigger than 2 cm.  Expanded indications include differentiated type EGCs bigger than 2 cm and selected cases of undifferentiated type EGCs.
This is a real world statistics. Among 355 early gastric cancers initially treated by ESD, 120 cases, this is 34 percent, belonged to the beyond absolute indication group. Some of them require surgery. Ten percent of patients in the absolute indication group were initially treated by surgery, and you can see the reason in the box at the right hand-side corner. Suspicious lymphadenopathy is the most common reason for surgery. 
In Korea, ESD candidates are usually selected by the absolute indications. After ESD, expanded criteria is applied to determine whether the resection was curative. There are controversies about the safety of ESD for expanded indication cases. It¡¯s partially because Korean studies consistently showed higher risk of lymph node metastasis in expanded indication cases than Japanese data. I¡¯ll show you some examples. 
Korean practice guideline for gastric cancer was just released. The first statement is about absolute indication. Endoscopic resection is recommended for well or moderately differentiated tubular or papillary early gastric cancers meeting the following endoscopic findings: endoscopically estimated tumor size <= 2cm, endoscopically mucosal cancer, and no ulcer in the tumor.
Let¡¯s talk about expanded indications. Do you think total gastrectomy was necessary for a 45 years old lady with 1 cm signet ring cell carcinoma? In my opinion, it was too much. Less invasive options should be considered. 
What would you recommend for a 40 years old woman with a small flat signet ring cell carcinoma?
I performed ESD and the final pathology was SRC, 10 mm, limited in the lamina propria layer, clear resection margins, and no lymphatic invasion.
ESD for expanded indication cases can be selectively performed in the individual cases. Flat small signet ring cell carcinomas are frequently treated by ESD in Korea.  
Statement 2 is about expanded indications. They say ESD could be performed, and the recommendation level was weak for. 
Next topic is the outcome. 
Outcome of endoscopic treatment of EGC with differentiated type histology is well established. We have ITT analysis such as comparison with surgery using propensity score matching. We also have PP analysis such as long-term follow-up data after curative resection or non-curative resection.
At my institution, we performed a propensity score-matching analysis between the two groups, endoscopic resection or surgery for differentiated type EGCs.
The overall survival was almost the same in the two groups. Because of the metachronous recurrences, disease free survival and recurrence free survival is better in the surgery group. However, there was no difference in the disease specific survival. 
Next evidence is the PP analysis. It¡¯s a single-arm long-term follow-up data for curatively resected differentiated-type EGCs. 
Excluding metachronous recurrences, we experienced only one case of local recurrence, and 2 cases of extragastric recurrences. 
This is the overall survival. There was no statistical difference between absolute indication and expanded indication.
There are the pictures of the two extragastric recurrences in our series. The top case belonged to the absolute indication group, and the lower case belonged to the expanded indication group.
Many centers recently reported long-term outcome after ESD in Korea. The rate of extra-gastric recurrence is usually less than 0.2%. 
After the publication, we experienced 7 more extragastric recurrences. And these are the picture just before the ESD. 
What¡¯s your opinion for this case?

This is another PP analysis for non-curatively resected differentiated type EGCs.  In cases with risk of lymph node metastasis, 70% were operated, and 30% were observed without surgery. 
In the surgery group, 11 have lymph node metastasis, which means 5.7%. 
In terms of the overall survival, additional surgery was related with better outcome. 
Survival benefit of additional surgery after non-curative resection was shown in a propensity matched study by doctor Eom at Korea National Cancer Center. As you can see at the right-hand side picture, the overall mortality of observation group was higher than that of the matched initial standard surgery patients.
Maybe we are doing too much surgery after ESD. Do you think surgery is necessary for mucosal cancer with lymphovascular invasion? As you can see in the red box, in lymphovascular invasion positive patients within the traditional absolute indication ? mucosal cancer, differentiated type, no ulcer, less than 2 cm, there was no lymph node metastasis in surgery. Careful observation without additional surgery can be an option for this group of patients.  
Final topic is education. 
There are 4 must knows before starting ESD. Indications and skills for careful endoscopic evaluation for candidate lesions, Advantages and disadvantages of each instrument, Strategies for technically successful ESD, How to manage complications. // And¡¦ Hands-on training must be side by side. 
There are so many different types of ESD knives in the market. We need to understand characteristics of each instrument. My favorite tool is Dual knife and IT-2 knife.
Recently we are also using Korean ESD knifes. Some of them have water-jet functions. 
This is my recent favorite ESD knife from a Korean company named Finemedix. It has IT-knife like function and Dual-knife like function at the same time. 
This case shows how I use the H type ESD knife. At first I start with I-type tip for marking and circumferential cutting. And than I change into O-type knife for speedy submucosal dissection. I think it can make the procedure quite short. 
Due to the time limitation, it is difficult to talk a lot about technical aspects of ESD. This is how I do the circumferential precutting with needle type knife - left side first, right side second, and finally horizontal cutting of the proximal part. 
Location also matters. In this case, en face view of the lesion is easy, but close up approach was difficult. 
So a large loop approach was used like this cartoon. 
Management of complications is a great part of ESD education. Most perforations can be treated endoscopically without surgery. 
When the resection is big and close to the cardia or pylorus, short-term oral steroid can be used for the prevention of obstruction. 
The hospital stay for gastric ESD is usually 4 days. 
For the beginners, hands on training using a pig stomach model is very useful. 
Before starting ESD for the first time, beginners should have some experience as the first assistant. With some cases, the main operator usually give the beginners to do part of the ESD steps. 
This ESD is the first procedure of my young fellow.  
Tele-mentoring using iPhone Facetime app is a very useful tool for ESD beginners. International mentoring is also possible. If you want some real-time comments from me, send me an e-mail (stomachlee@gmail.com).
Finally, I¡¯d like show you a unforgettable case. 
I performed an ESD procedure in a surgical ICU. The patients was on ECMO due to dilated cardiomyopathy and was waiting for cardiac transplantation. 
During the pre-cardiac transplantation workup, an early gastric cancer was found. So I performed an ESD at a surgical ICU. 
The procedure was done as usual, but the problem was delayed bleeding. The patient cannot stop warfarin. Anyway after a successful cardiac transplantation, the patient is still doing well. 
Ladies and gentlemen, I¡¯d like to conclude my presentation by saying that ESD is widely performed for EGCs in the absolute indication in Korea. Annually, it¡¯s more than 7,000 cases. We are still very careful about expanded indication cases. It¡¯s done usually for flat SRCs less than 1 cm. Starting the role of the first assistant is the beginning of learning ESD techniques.