Current Status and Reflections on Surgical Treatment of Gastric Cancer
Since the first successful resection of gastric cancer in Billroth a century ago (1881), the surgical treatment of gastric cancer has a history of more than 100 years. After decades of exploration and experience, people have gradually realized that radical surgery is the primary means of gastric cancer treatment, and the new concept of gastric cancer treatment in the last decade or so is mainly updated on minimally invasive surgery for early gastric cancer and improving patients’ postoperative quality of life, instead of pursuing postoperative survival as a single goal.
1. The basic consensus of gastric cancer surgical treatment: at the end of gastric cancer surgery, cancer residue visible to the naked eye is R2 resection, cancer residue found microscopically is R1 resection, and no evidence of cancer residue is R0 resection. Radical surgery for gastric cancer is curative only if R0 resection is achieved, otherwise it is palliative treatment[1] . Surgical method, lymph node metastasis status and tumor stage are the prognostic factors affecting the postoperative survival time of gastric cancer; R0 resection is beneficial to prolong the postoperative survival time and is an independent prognostic factor for gastric cancer. It can be seen that the basic principle of radical gastric cancer surgery is R0 resection. This requires an adequate extent of gastrectomy and lymph node dissection, as well as the necessary resection of adjacent organs or tissues, and Krukenberg’s tumor and pelvic peritoneal implantation are both pelvic metastases of gastric cancer, which are poor prognosis of stage IV gastric cancer, but a more thorough surgery can still significantly improve the prognosis of patients if the conditions for total resection of the lesion are available[2] .
1.1 Scope of gastrectomy: The scope of gastrectomy for radical gastric cancer mainly depends on the tumor site, the depth of infiltration and the distance from the cutting edge. For pyloric gastric cancer and gastric sinus cancer, if the tumor margin is ≥5 cm from the proximal surgical margin, distal gastrectomy is feasible; otherwise, total gastrectomy is performed. Proximal gastric cancer, gastric body cancer, diffuse gastric cancer, and distal gastric cancer invading the gastric body are subject to total gastrectomy. Most scholars recommend the following indications: ① clear metastasis is found in the lymph nodes of the second station, and according to the principle of D>N, expanded lymph node dissection to the third station; ② invasion of adjacent organs or clear lymph node metastasis in the immediately adjacent organs of gastric cancer foci, such as splenic gate; ③ no distant metastasis; ④ no important organ dysfunction (iv) no important organ dysfunction. On this basis, we strive to achieve R0 resection by surgery, and together with other comprehensive treatments and postoperative adjuvant chemotherapy and radiotherapy, we can expect to further improve the prognosis of patients. [3] . Gastric cancer radical surgery with more than 2/3 of gastrectomy and D2 clearance of lymph nodes is named as standard radical surgery, and the above selection criteria for the extent of gastrectomy are supported by sufficient evidence-based medicine and can be used as clinical guidelines for the treatment of gastric cancer [4].
1.2 Lymph node contouring: The extent of lymph node dissection is one of the differences between the surgical treatment of gastric cancer in Eastern and Western countries. In Japan, D2 or D3 lymph node dissection is the standard surgery for gastric cancer, and its 5-year survival rate is significantly better than that in Western countries. In Europe and the United States, D1 lymph node dissection is the standard procedure for gastric cancer.6 In 2006, Wu, Chiu-Wen et al. in Taiwan reported for the first time a prospective randomized comparative study on the extent of lymph node dissection for gastric cancer, and the results showed that the overall 5-year survival rate of patients undergoing D2 surgery was significantly better than that of patients undergoing D1 surgery, and this strong evidence led scholars in Western countries to believe that there was no need to conduct further prospective randomized comparative studies to prove that D2 surgery was superior to D1 surgery. The incidence and mortality rates of gastric cancer in Western countries are quite different from those in China, Japan, and Korea, and differences in age groups and ethnicity and dietary habits are some of the factors [7]. Another point is that the morbidity and mortality rates and complication rates of D2/D3 lymph node dissection in Europe and the United States are much higher than those in Japan and China [8]. In fact, the key factor affecting the morbidity and mortality rates and complication rates of D2/D3 lymph node dissection is the surgeon’s surgical experience. The most commonly used lymph nodes are 16 and are subdivided into 3 stations according to the tumor site and different areas, and the unsatisfactory lymph node clearance areas will have to be hoped for on top of postoperative radiotherapy [9]. The learning curve of total gastric D2 resection shows that after more than 30 total gastric (D2) resections or 6 months of study at a large gastric cancer center, gastric cancer surgeons can reduce surgical morbidity and mortality and complication rates to an acceptable level, which is more about perioperative management than surgical skills.
1.3 Combined organ resection: Proximal gastric and cardia cancers require resection of the lower esophagus to achieve negative margins. In the past, the scope of lower esophageal resection was not clearly defined. In recent years, foreign scholars have shown that resection of the lower esophagus ≥6 cm for proximal gastric and cardia cancers can guarantee negative lower esophageal margins, and the surgical results of many tertiary hospitals in Japan and China have shown that resection of 4-5 cm of esophagus is sufficient for gastric cancer invading the esophagus, and R0 resection has been achieved with no postoperative pathological evidence of microscopic residue. It is also very easy to expose 5-7 cm of esophagus after vagus nerve dissection.
In earlier years, radical resection of gastric cancer combined with pancreatic tail resection was performed to remove the lymph nodes around the splenic artery (No. 11), but the incidence of complications such as pancreatic fistula and subdiaphragmatic abscesses increased.10 In 1995, the Japanese Research Society for Gastric Carcinoma (JRSGC) proposed to preserve the In 1995, the Japanese Research Society for Gastric Carcinoma (JRSGC) proposed a procedure to preserve the pancreas and remove the lymph nodes around the splenic artery (No. 11), which was soon popularized. Since then, left hemipancreatic resection is no longer a routine procedure for radical gastric cancer, and cancer penetrating the plasma membrane and invading the pancreas is the only indication for combined pancreatectomy [11]. Combined resection of the spleen has been controversial. The purpose of spleen excision is to remove the splenic hilar lymph nodes (No.10), which can achieve R0 resection. In contrast, opponents believe that there is no significant difference in the long-term survival rate between patients with spleen excision and spleen-preserving gastric cancer, but there is a significant difference in the complication rate and in-hospital morbidity and mortality rate between patients with spleen excision and spleen-preserving gastric cancer after surgery, probably because the spleen has a pivotal role in human immunity, and whether to combine splenectomy in radical gastric cancer surgery should be an individualized plan.
2.Reduction surgery for early gastric cancer
Early gastric cancer refers to gastric cancer confined to the intramucosa (m) or submucosa (sm) layer without considering the presence of lymph node metastasis [12], but a few patients also have lymph node metastasis. Regardless of the presence or absence of lymph node metastasis, the prognosis of early gastric cancer is significantly better than that of progressive gastric cancer. In fact, all patients with progressive gastric cancer go through the stage of early gastric cancer, only that not many of them are detected or diagnosed during this period. The difference in detection rates between China and Japan is mainly due to the difficulty of implementing gastroscopic screening, and the high detection rate depends on the improvement of diagnostic level and clinical screening. In the 1980s, surgery for early gastric cancer was also mostly performed by standard D2 resection. Today, more than 20 years later, the treatment of early gastric cancer has undergone significant changes.
2.1 Endoscopic treatment of early gastric cancer (EGC): Endoscopic gastric mucosal resection was first reported by Japanese scholars in 1984 for the treatment of early gastric cancer, and has been used for more than 20 years for elderly patients who refused open surgery and had severe concomitant diseases. Nowadays, endoscopic gastrectomy is generally accepted worldwide and is expected to become the standard treatment for early gastric cancer. The main indications are well-differentiated intramucosal carcinoma. Without accurate preoperative gastric cancer staging, endoscopic mucosal resection (EMR endoscopic mucosal resection) or ESD (endoscopic mucosal dissection) is not appropriate[13] . Therefore, it has been suggested that endoscopic mucosal dissection for early gastric cancer is not safe and laparoscopic gastrectomy may be a better option . In China, endoscopic gastric mucosal resection for early gastric cancer has not yet been widely performed, and the postoperative pathology of this method can determine the depth of cancer infiltration, whether the blood vessels are involved and whether there is cancer residue at the cut edge. The indications are: (1) Type I and Ha carcinoma of less than 20mm to the naked eye; (2) depressed carcinoma of less than 10mm and no ulcer to the naked eye. The scope of resection should be in accordance with the “2cm principle”. For areas where conventional mucosal resection is more difficult, lesions located in the posterior wall of the gastric lesser curvature and cardia can be solved by endoscopic ligature resection. Today, when the conflict between doctors and patients is so acute, the application must be chosen with great care.
2.2 Laparoscopic surgery for early gastric cancer: Laparoscopic surgery for early gastric cancer includes laparoscopic partial gastrectomy and laparoscopic assisted gastrectomy, etc. Because of the technical difficulty and lack of evidence-based medicine, laparoscopic gastrectomy for gastric cancer is not as widely accepted as laparoscopic colectomy, and laparoscopic technology in most hospitals in China is only in the hands of a few surgeons, and the routine of senior professors Open surgery, which is not very traumatic and fast, incorporates tumor-free operation with venous blood flow blockage, and the shortening of anesthesia time fails to make laparoscopy manifest its extraordinary charm, but can only be used as an investigational surgery for the time being, and its exact value and safety are yet to be further confirmed[14] .
2.3 Scope of gastrectomy for early stage cancer: Gastric cancer reduction surgery according to the Japanese gastric cancer treatment outline refers to partial gastrectomy, segmental gastrectomy and pylorus preserving gastrectomy. The indications for partial gastrectomy and segmental gastrectomy are submucosal carcinoma without lymph node metastasis, and it is required that no regional lymph node metastasis must be determined during surgery. For bulging mucosa ≤20 mm and bulging submucosa ≤10 mm, local gastrectomy without lymph node dissection can be performed, and the extent of resection follows the “3 cm principle”, i.e., the resection margin should be more than 3 cm from the tumor margin, and enough lymph nodes visible to the naked eye should be removed according to the intraoperative situation. In order to determine whether there is cancer metastasis in lymph nodes, HE staining or immunohistochemical staining of cytokeratin in a single section, it is difficult to achieve 100% intraoperative rapid pathological examination. Therefore, partial gastrectomy and segmental gastrectomy have the risk of cancer residue. The surgical indications for pylorus preserving gastrectomy are not yet unified, and the vagus nerve must be preserved or not damaged during surgery in order to preserve the pylorus and its function, which may affect the thoroughness of lymph node dissection (N3,N4,N5).
2.4 Extent of lymph node dissection: The reduction of the extent of lymph node dissection is relative to the standard D2 dissection and includes reduction procedure A (MGA: modified D1 radical surgery) and reduction procedure B (MGB: modified D2 radical surgery). The indications for reduction surgery A are: (i) intramucosal carcinoma without lymph node metastasis; (ii) differentiated diameter Carcinomas of the Gastrointestinal Tract. Updated: Jul 21, 2008
[8] . D. Max Parkin, MD, Freddie Bray, J. Ferlay and Paola Pisani, PhD. Global Cancer Statistics, 2005 American Cancer Society .2002, Cancer J Clin 2005; 55:84- 106.
[9]. [25]. Radiation and Chemotherapy After Surgery Improves Survival in Stomach Cancer . N.C.I, Reviewed: 03/09/2005.
[10]. [11]. [19]. Ho YL. Problems of combined pancreatic and splenic resection in radical surgery for gastric cancer. Surgical Theory and Practice, 2008, 13(1): 9-10.
[12]. [13]. [15]. Ji Jafu, Bu Zhaod. Rational selection and evaluation of reduction surgery for early gastric cancer. Chinese Journal of Practical Surgery, 2008, 28(9): 725-727.
[14]. Lee, Wei-Jei; Wang, Weu; Chen, Tai-Chi; Totally Laparoscopic Radical BII Gastrectomy for the Treatment of Gastric Cancer: A Comparison With Open Surgery . Surgical Laparoscopy Endoscopy & Percutaneous Techniques. August 2008. 18(4):369-374,
[16][17]. You JQ, Ma LIL. Study on the application of sentinel lymph node biopsy technique and micrometastasis detection for gastric cancer. Chinese Journal of Practical Surgery, 2009, 29(4):333-336.
[18]. Chinese Medical Association Surgical Surgery Group. Expert consensus on gastrointestinal anastomosis. Chinese Journal of Practical Surgery, 2008, 28(10): 810-812.
[20]. Hartgrink HH,Velde CJH,Putter H,et al. Extended lymph node dissection fro gastric cancer:who may benefit? Final results of the randomized Dutch Gastric Cancer Group Trial.J Clin Oncol,2004,22:2069-2077
[21]. Lin Y. C., Zhu C. G., Zheng M. H.. Perspectives on the diagnosis and treatment of gastric cancer in the new century. Surgical Theory and Practice, 2008,13(1):1-3.
[23]. Wu Z. D., Wu Z. H. Surgery. 7th edition, Beijing: People’s Health Publishing House, 2008, 1: p439-440.
[24] LU, WANG ZN, SUN Zhe, et al. Clinicopathological characteristics and prognosis analysis of gastric cancer in young people. Chinese Journal of Surgery, 2008, 46(19): 1468-1470
[26]. Nang Songmiao, Ou Xilong, Sun Weihao, et al. Relationship between the expression of cyclooxygenase-2 and angiogenesis in pancreatic cancer tissues. Tumor, 2008, 28(9): 791-794.