Gastric cancer is a common malignant tumor in China with a high incidence and mortality rate. Despite years of research, as with other tumors, what was once expected to be tackled in the 1980s was pushed back again to the year 2000, and as you can see, how? Now customers are being pushed back once again to 2050. The rapid development of human technology, especially the deciphering of the human genome has excited the world, and now a large number of gene therapies and drugs have emerged in response, but the results are still unsatisfactory. The hope of human beings to overcome tumors is still waiting for a long time. So far, surgery is still the only way to cure gastric cancer, and despite the emergence of multiple treatments, surgery is still the top priority.
Due to the extensive development of gastric surgery, a variety of gastric resection and reconstruction methods are now more mature, and the radical resection of primary lesions of gastric cancer (gastrectomy) is easier, but the main problem lies in the removal of metastatic lesions of gastric cancer.
1.Historical development of gastric cancer surgery
In fact, the early surgical treatment of gastric cancer originated from the basic understanding of anatomy and pathology in the West, with the main purpose of removing obstruction and stopping hemorrhage. The surgery was aimed at the lump seen by the naked eye, and today we know that it is absolutely difficult to achieve the purpose of cure. Because the basic cells of a tumor are very small and require a microscope to see, a matchhead-sized cell population has 30 million cells, which I often compare to concrete powder for the sake of description. These cells can grow like special forces or become divisional formations, and at a certain time or space they can migrate to other places to form new lesions, which are metastases. With the development of comprehensive science and technology, especially the development of pathology, gastroscopy, CT, ultrasound, the increase of surgical treatment for early and mid-stage gastric cancer patients and the deepening of related research, the understanding of surgical treatment of gastric cancer has moved from the general resection of large parts of the stomach to the radical surgery with the purpose of lymphatic clearance, and from the concept of resection of masses only seen by the surgical eye to the concept of resection of metastases. From the concept of resection of the mass seen by the surgical eye to the concept of cell removal by treating the primary lesion and metastatic tumor cells together, such as extensive lymphatic clearance and abdominal exfoliative cell killing, we can see the historical development process of gastric cancer treatment, from simple to complex, from scattered to systematic and specialized treatment.
2.The current situation of gastric cancer surgery in China
In our country, in the past, due to poverty and the absence of drugs such as Loxac, a large number of patients with gastric ulcers appeared, duodenal ulcers received surgical treatment, and major gastric resection used to be a basic surgical procedure to train introductory surgeons widely carried out in county, city and even district and rural hospitals. However, now that gastric cancer has become a common tumor and must be treated surgically, the original surgical method of removing only the primary lesion of the stomach has become the basic reality of gastric cancer surgery in China. From the study of lymph node metastasis of gastric cancer in the 1950s to the formation of a consensus on the necessity of lymph node dissection for gastric cancer in the 1980s, and even in the 1990s, China has been implementing the standard of D2 surgery according to international standards for many years, but so far, the complexity of lymphatic metastasis of gastric cancer and the high difficulty of dissection surgery have made it difficult to be widely implemented. This coincides with the long-term low survival rate of gastric cancer treatment in China, which indicates that the status quo of gastric cancer treatment in China is poor.
3. Causes of the current confusing situation of gastric cancer surgery
Even the standard D2 surgery, which is vigorously promoted, is extremely confusing under the influence of today’s individualized treatment thinking, which is manifested by the ad hoc decisions made by specific doctors during surgery, and there are surgeries called D1, D1+, D2+, D3, D4, etc. How can we talk about standard surgery? The fundamental reason for the confusion lies first of all in the specificity of gastric cancer itself, i.e. the complexity of gastric cancer cell metastasis. It is like a big tree, the cancer cells can flow along the microtubule system in the trunk to the root system it belongs to, which can be divided into three levels of root system, the key is that it routinely develops in the first level of root system now and then develops in the deeper root system later, but it often appears to leap from the primary site or shallow root system to the deeper root directly. Due to the influence of the size of the tumor group it is simply impossible to accurately determine whether there is metastasis in the lymph nodes.
The decision to rely solely on the surgeon’s decision based on the prevailing conditions can guarantee the implementation of the standard and prevent the residual metastatic lymph nodes from making the surgery a palliative resection, which directly affects the patient’s postoperative survival. The second reason is that our doctors care too much about learning from foreign sources, including the Japanese staging system and the UICC/AJCC staging system in Europe and the United States, and as soon as a new version appears, a national climax will be formed, just like the national climax of studying the new version of Mao Xuan. This is in line with the impetuous wind of all circles in China today.
This is in line with the impetuous trend in China today. However, it has caused confusion in the national specialty surgery for gastric cancer, and then ended up with the title: individualized treatment! Similarly, the analysis of treatment results also directly leads to the confusion of statistical data, especially the distortion of staging, such as how to judge its stage without D4 surgery, the only way is to assume that there is no metastasis in the lymph nodes next to the abdominal aorta; without completing D2 surgery, the same can only assume that there is no metastasis in the lymph nodes of the second station for staging statistics.
4.The necessity of regional lymphatic dissection for gastric cancer and the metastatic characteristics of gastric cancer
From the treatment point of view, gastric cancer surgery has only one chance, unlike benign diseases that can be operated again. Surgeons should treat gastric cancer surgery from a cytological point of view rather than a mass point of view, and carry out the concept of tumor-free surgery all the time, not only to prevent medical dissemination during surgery, but also based on the cellular concept of radical resection. Based on the cytological basis, when the cure of gastric cancer still relies on surgery, there are only two outcomes after surgery, advanced stage with residual tumor cells after surgery and early stage without residual.
Surgery is unable to perform radical resection for patients who have developed metastatic lesions. Clinical studies on gastric cancer since the 1950s have also demonstrated that the lymphatic metastasis of gastric cancer follows a certain pattern, forming a relatively independent regional lymphatic drainage system around the stomach with a 3-level lymph node network as the basic structure. Further studies have shown that lymphatic metastasis of gastric cancer is very complicated, with many influencing factors, and lymphatic metastasis is uncertain, and there are both regular and often irregular phenomena. The frequency and distance of lymph node metastasis increase sequentially as the depth of gastric cancer invasion deepens. Since the patients with gastric cancer found clinically are progressive cases, the lymphatic metastasis rate reaches 70-80%, the second station is often involved, and 1/3 of them will be metastasized to the parietal aorta, and because the lymph nodes of stations 1, 2 and 3 have the end point of lymphatic vessels regional lymph nodes Because the lymph nodes of stations 1, 2 and 3 have direct traffic with the endpoints of the lymphatic vessels (group 16), “jump” metastases may occur.
Our data showed that 3/4 of the positive lymph node metastases in group No16 originated from the gradual metastasis of conventional lymph node stations, while 1/4 of them were jump metastases. We also demonstrated that complete surgical resection of the primary site of gastric cancer and its associated regional lymph nodes is the main means to improve the 5-year survival rate of patients.
I believe that the stratified grouping of gastric lymph node network and gastric cancer lymphatic metastases are relative, although a small number of cases can suggest the presence of tumor metastasis in the para-aortic lymph nodes based on the enlargement and hardening of No16 or abnormal color, but based on the cytological point of view, although there are factors such as tumor growth pattern, general type, degree of differentiation, depth of invasion, and tumor size to help us determine the probability of lymph node metastasis in the No16 group. Even the so-called nano-carbon tracer technique promoted by some people is just a high-tech gimmick, because only some of the lymph nodes with structural changes will show carbon deposition, while a large number of relatively small cell populations or lymph nodes with complete structural changes will not be shown.
Therefore, in view of the complexity of gastric cancer cell metastasis, the stomach itself and its relatively independent lymphatic drainage system, including the abdominal para-aortic lymphatic network, should be considered for removal as a whole when performing radical gastric cancer surgery, i.e. resection of the primary lesion of gastric cancer and regional lymphatic dissection.
5.Status and difficulty of regional lymphatic dissection
D1, D1+, D2+, etc. are different degrees of gastric regional lymphatic dissection surgery, but they are typical opportunists of radical surgery, as a doctor with the mission of saving lives, he should not be opportunistic, but should try his best to achieve perfection. The upper part of the lymph node dissection of the abdominal para-aortic lymph nodes in the gastric region involves complex anatomical relationships, including the inferior vena cava, the left renal vessels, the portal vein, the celiac artery, the superior mesenteric artery and the inferior phrenic artery, as well as the abdominal nervous system, the left adrenal gland and its vascular branches.
Special attention needs to be paid to the careful dissection during surgery and to the appropriate management of some variant vessels. Moreover, tumor metastasis is carried out on a cellular basis rather than as a visually visible mass. At the time of surgery, it is possible that the metastatic tumor cells are also located in the widely dispersed lymphatic network around the stomach or in very small lymph nodes, so the perigastric lymphatic clearance is not the removal of a few lymph nodes but the complete clearance of the lymph nodes in the gastric drainage area and their network system. From our practice and the experience of domestic and foreign colleagues, it is more convenient to perform D4 surgery through the right posterior abdominal approach, and if the operation is performed according to the anatomical level, with careful and gentle operation, reliable ligation, and complete hemostasis, there is usually no major bleeding or serious complications. Since the Japanese scholars carried out expanded lymph node dissection in the 1980s, the complication rate of D4 surgery has not differed from that of D2 and D3 as the technique has become more proficient, and the in-hospital mortality rate is only 0.8%, and the results of the study are satisfactory. Of course the results of gastric cancer surgery with or without specialized training (surgical experience both personal and hospital) show significantly different surgical mortality and complications, so the need for specialized training of surgeons in gastric cancer surgery is emphasized.
Therefore, the authors concluded that resection of the primary lesion and complete clearance of the relatively independent gastric lymphatic drainage system is the standard surgery for gastric cancer. Regional lymphatic dissection of gastric cancer should be emphasized both for surgical treatment and for the statistical needs of surgical outcomes.