Gastroenterological surgery in Japan: The past, the present and the future

Abstract In the last two centuries, there has been remarkable progress in the field of gastroenterological surgery, including the curative resection of cancers, replacement of failed organs through transplantation, increased safety of undergoing major surgeries and decreased operative morbidity through developments in minimal access surgery. Japan has very much been at the forefront of these advances, as is evident from the present review, from advancing the surgical management of gastric cancer to the pioneering work in live‐donor transplantation. This review also highlights many instances where surgical management of the same pathologies has evolved differently between Japan and the West. It is encouraging that many procedures established in Japan are eventually taken up by the West, often after rigorous assessment affirming the quality and applicability of such techniques. In Japan, many of the crucial issues in gastroenterological surgery are increasingly addressed through large multi‐institutional prospective control trials, ensuring that Japanese surgeons continue to contribute to the advances in gastroenterological surgery.


| INTRODUCTION
In 1804, Hanaoka Seish u began carrying out surgery under general anesthesia; he is widely acknowledged for being the first to do so, well before the first ether anesthetic was given by Crawford Long in 1842. This was a remarkable achievement considering that Seish u developed the general anesthetic himself, based on his knowledge of Chinese herbal medicine. He combined this with the European surgical techniques he had learned through apprenticeships, which were introduced to Japan at the time by the Dutch. Although the first operation he carried out was the removal of breast cancer, he went onto carry out many other procedures including treatment of hemorrhoids and fistula-in-ano. 1 What Seish u achieved reflects the way in which the field of gastroenterological surgery has developed in Japan since his It is an honor to be able to highlight some of the most notable achievements made by Japanese surgeons in the modern era, that have also had a global impact in the field of gastroenterological surgery. We apologize for omitting much of the significant and groundbreaking work as a result of the constraints of the length of this article. We are at the same time very proud of the achievements made by our colleagues of the past and the present. In analyzing the achievements to this date, we will also reflect on how we can move forward in the future to continue making advances in gastroenterological surgery.

| ESOPHAGEAL SURGERY
The first successful esophagectomy for carcinoma of the thoracic portion of the esophagus was conducted by Torek in 1913, 2 but the procedure was associated with a very high mortality rate for many decades thereafter. In the middle of the 20th century, Nakayama achieved a strikingly low operative mortality rate of 16.7% (five of 30 individuals) in patients undergoing esophagectomy for cancer, 3 aided by the use of endotracheal anesthesia and perioperative intermittent positive pressure ventilation. This was the lowest ever mortality rate to be reported at the time. The operative mortality rate fell further, partly as a result of Nakayama promoting the undertaking of esophagectomy and reconstruction over different time points, thereby limiting the operative stress. 4 In Japan, since the early 1980s, a large proportion of esophageal cancers have been managed by three-field lymph node dissection, 5 based on data suggesting that the rate of isolated cervical lymph node metastasis could be as much as 40% in patients with squamous cell carcinoma. 6 Large nationwide observational studies of patients who have undergone three-field lymph node dissection have since confirmed that approximately one-third of the patients harbor metastasis in the cervical nodes. Also, the overall long-term survival was better in those who underwent three-field compared to two-field lymph node dissection, with comparable and low perioperative mortality rates. 7,8 The benefits of carrying out three-field lymph node dissection have been viewed largely with scepticism in the West, because of the high rate of morbidity associated with this procedure, as well as the perception that the cervical lymph nodes are less likely to be involved in adenocarcinomas, which occur more commonly in the West and in the lower esophagus. However, a recent report by Altorki et al. 9 from a large prospective observational study showed that approximately one-third of patients with esophageal cancer had otherwise unsuspected cervical node involvement regardless of the histological type, and that three-field lymph node dissection was associated with better long-term overall survival. Therefore, in the future, three-field lymph node dissection may become more frequent for treating esophageal cancer outside of Japan.
Although three-field lymph node dissection has led to improvements in long-term survival, surgery alone is associated with a lim- In the West, neoadjuvant chemoradiotherapy has become the standard treatment after being shown to be superior to chemotherapy alone when carrying out two-field lymph node dissection for adenocarcinoma. 10 The role of adjuvant therapy for squamous cell carcinoma of the esophagus for patients who receive three-field lymph node dissection has been explored in several multi-institutional randomized control trials in Japan. Survival benefit with adjuvant chemotherapy for esophageal cancer was first demonstrated, and a subsequent trial went on to show that neoadjuvant chemotherapy was superior to adjuvant chemotherapy in terms of overall survival, and the former has now become the standard treatment in Japan. 11 The role of radiotherapy in addition to chemotherapy in the context of three-field lymph node dissection for squamous carcinoma of the esophagus is still a matter of debate, and is being addressed in an ongoing nationwide randomized control trial by the Japan Clinical Oncology Group. 12 3 | GASTRIC SURGERY Japanese surgeons have arguably had the most influence worldwide on the way gastric cancer surgery is carried out. The practice of gastrectomy with extended lymphadenectomy for gastric cancer was established in Japan and provides the foundation for effective treatment of this disease. 13 In 1989, Maruyama et al. 14 published the largest and most detailed work concerning lymph node metastasis in gastric cancer, and then later demonstrated the effectiveness of extended lymphadenectomy for gastric cancer. 13 In the West, the higher prevalence of proximal gastric cancers, and patient factors such as older age, higher body mass index and higher incidence of comorbidities make the surgical management more challenging, [15][16][17] has perhaps resulted in the tradition of carrying out a more limited lymph node dissection. Despite this, there is now a wider uptake of extended lymphadenectomy in countries other than Japan, and this is thought to be behind the significant improvement in long-term survival. [18][19][20][21][22] More recently, in Japan, a number of well-powered multi-institutional studies have evaluated the feasibility and the benefits of going beyond the field of dissection of D2 lymphadenectomy.
Sasako et al. 23 26 showed that splenectomy for patients with proximal gastric cancer that does not involve the greater curvature was associated with increased morbidity without improving the overall 5-year survival. These studies have thus been informative in defining the extent of dissection that should take place for gastric cancer.
Japanese surgeons have also sought ways to minimize the morbidity and mortality associated with carrying out gastrectomy. In 1994, Kitano et al. 27 reported the first laparoscopic Billroth I gastrectomy and since then, gastrectomy is increasingly being carried out laparoscopically and in some cases, robotically in Japan. 28

| END OSCOPIC TR EATMEN T OF GASTROINTESTINAL CANCERS
For the treatment of early gastric cancer, endoscopic mucosal resection (EMR) is now well established in Japan. Data from Ono et al. 56 included 479 gastric cancers treated by EMR and showed that 69% of these could be resected with a clear margin. Most importantly, the cancers without a clear resection margin could go on to be surgically resected or followed up endoscopically without any cancer-related deaths, thereby showing that this less invasive approach could be carried out without compromising the cure rate.
The latest method of endoscopic resection is endoscopic submucosal dissection (ESD), which allows for en bloc excision of early gastrointestinal malignancies, whether in the stomach, esophagus or large intestine. ESD enables a more accurate assessment of the depth of tumor invasion, allowing for more accurate prediction of the risk of lymph node metastasis. Cancer recurrence rates are very low after ESD, which has become an established practice for the treatment of early gastric and esophageal cancers in Japan, and is increasingly becoming used for early colorectal cancer. 57 ESD is slowly becoming established in the West, suggesting that it will eventually become widely used worldwide.

| CONCLUDIN G REMARKS
Japanese surgeons have contributed significantly to the advancements in the field of gastroenterological surgery, including the way in which lymph node dissection is highly systematized and if necessary extensive for the management of gastroenterological malignancies. It is very encouraging that important surgical issues are increasingly being addressed through well-designed randomized control trials. The present article illustrates many instances where surgical management of the same pathologies has evolved differently between Japan and the West, thereby making it even more important that Japanese surgeons continue to evaluate their practice rigorously and share their data with the rest of the world.

CONFLI CTS OF INTEREST
Authors declare no conflicts of interest for this article.