Stomach cancer is a disease that seriously endangers people’s health, and the annual incidence rate of stomach cancer in China is about 60/100,000. The incidence rate of gastric cancer in China is about 60/100,000 per year, and the death rate is about 30/100,000, ranking the 1st among all malignant tumor deaths. Compared with developed countries in Japan, most patients with gastric cancer in China are already in the progressive stage when they are diagnosed, and the proportion of early gastric cancer is less than 10%. In the comprehensive treatment of gastric cancer, surgical resection is still the main means of treatment. Early detection and radical resection can improve the survival rate, and for early limited gastric cancer, the 5-year survival rate of surgical treatment can reach 90%. If there is no lymph node metastasis, adjuvant chemotherapy before and after surgery is not advocated. Early lymphatic system, hematologic system and peritoneal metastasis limit the effect of surgery, and the long-term survival rate of gastric cancer after surgery is low. Even in Japan, where the treatment effect of gastric cancer is better, the 5-year survival rate of patients with stage III/IV gastric cancer is only about 27%. Even in early gastric cancer, the infiltration is limited to submucosa or superficial muscle layer, there are still 2%-5% of patients with lymph node metastasis, and even more patients with micro metastasis. After radical resection of gastric cancer, many patients still die from local or intra-abdominal recurrence and distant organ metastasis. Chemotherapy is required for patients who have lost the opportunity of surgical resection or cannot undergo radical surgery, or for those who have recurrence or/and metastasis after surgery, as well as for those who have residual gastric cancer. Chemotherapy is one of the main treatments for advanced gastric cancer, and it can improve the quality of life and prolong the survival of patients with advanced gastric cancer compared with supportive therapy. There is no worldwide standard chemotherapy regimen for advanced gastric cancer. In the past two decades, chemotherapy for gastric cancer has developed rapidly, and new anticancer drugs such as anthracycline antibiotics, platinum compounds and glucosamine, known as the “Three Musketeers”, have been introduced continuously; new combination chemotherapy regimens characterized by high efficacy and low toxicity have emerged; in vitro drug sensitivity tests for gastric cancer have come out of the laboratory and played a guiding role in clinical chemotherapy. A series of new technologies and treatment methods have been developed to improve the surgical resection rate and radical resection rate of gastric cancer, prevent metastasis and reduce recurrence, such as preoperative, intraoperative and postoperative adjuvant chemotherapy, early postoperative intraperitoneal perfusion chemotherapy and early postoperative intraperitoneal warm perfusion chemotherapy, which have significantly improved the surgical treatment effect of gastric cancer and significantly increased the 5-year survival rate after surgery. In recent years, a large number of relevant clinically relevant studies have been conducted around new third-generation drugs such as 5-FU prodrugs (e.g., Siroda, S-1 (gefitinib)), paclitaxel and irinotecan. Very good efficacy has been achieved. I. Correct view of the role of chemotherapy The main reasons for the failure of gastric cancer treatment can be three: firstly, incomplete local treatment or local or peritoneal recurrence after unsuccessful treatment; secondly, distant metastasis; and thirdly, reduced immune function of the body. The current chemotherapy cannot cure gastric cancer, but it seems to have a definite role in eliminating microscopic lesions, improving the effect of surgical treatment, and reducing recurrence and metastasis, except as palliative treatment. Therefore, conditions should be actively created to combine chemotherapy with surgery, especially for those gastric cancer patients who cannot be treated surgically according to the traditional view, we should strive to improve the chance of surgical resection and cure through preoperative chemotherapy, i.e. neoadjuvant chemotherapy. Most chemotherapeutic drugs have large toxic side effects. When administering chemotherapy, a thorough understanding of drug factors (including drug type, dose, treatment route and schedule, cell reversal and pharmacokinetics, drug membrane permeability and arrival, drug activation and non-activation, major toxic side effects, etc.) should be obtained. Host factors (including general condition, age, peripheral blood and bone marrow function, immune status, etc.) and tumor factors (type of gastric cancer, biological behavior, degree of spread and infiltration, drug resistance, etc.), and deal with the interrelationship among drug, host and tumor. In the process of chemotherapy, the development and changes of the relationship between these three factors should be constantly analyzed and mastered, so as to promote the synergistic aspects of these factors, which are conducive to eliminating cancer cells and reducing the damage to the host, with the aim of killing more or all cancer cells while avoiding “chemotherapeutic death” (chemotherapy death). For example, patients with good general condition, bone marrow and immune function, who have not been treated with chemotherapy before, but mainly adenocarcinoma cells, are good candidates for chemotherapy; for example, elderly patients over 65 years old, with weakened general condition, white blood cells below 3×109/L and platelets below 8×1010/L, who have been treated with a large number of anticancer drugs or radiotherapy, should be cautious or generally not easy to perform chemotherapy again. From the perspective of biological behavior of gastric cancer, confined, mass-growing, highly differentiated adenocarcinoma is prone to liver metastasis, so in addition to general chemotherapy principles, treatment measures to prevent liver metastasis should be considered; infiltrating, diffusely growing, poorly differentiated gastric cancer is prone to intra-abdominal spread, so in addition to systemic chemotherapy, intra-abdominal administration should be considered. The selection of chemotherapy regimen should follow NCCN treatment guidelines, follow evidence-based medicine, and adhere to the principles of individualized and standardized treatment. Most doctors who used chemotherapy for gastric cancer in the past chose chemotherapy regimens based on their own experience, which is highly subjective and does not conform to the principle of individualized drug use. Recent studies over the past decade or so have shown that the results of in vitro drug sensitivity tests for gastric cancer have good correlation with clinical efficacy, which can be used to guide the selection of drugs for patients and formulate more scientific and reasonable chemotherapy regimens. Our hospital has carried out cell culture of biopsy tumor tissue, predetermined multiple groups of chemotherapy regimens, conducted sensitivity tests of corresponding chemotherapy regimens, and selected sensitive chemotherapy regimens to be applied to this patient, which achieved good efficacy. V. Establish the concept of quantity and time The effect of chemotherapy is inversely proportional to the number of tumor cells. When the number of tumor cells in the organism is the least, the effect of chemotherapy is the best. If the number of gastric cancer cells is small, chemotherapy should be started as early as possible. For patients who are not suitable for radical surgical resection, palliative resection or other measures should be adopted to reduce the number of tumor cells and tumor load, so as to provide conditions for the success of chemotherapy. In the past, due to excessive concern about the toxic side effects of chemotherapy drugs and their influence on wound healing, surgical chemotherapy for gastric cancer was usually started only 4-6 weeks after surgery. Recent studies have found that the blood vessels and fibrous connective tissues in the abdominal cavity after gastric cancer surgery encapsulate free cancer cells within a short period of time, and the later the drug is used, the less likely the cancer cells will be killed. The multiplication period of gastric cancer cells is about 40-60 days. In order to achieve the best chemotherapy effect, it is currently advocated that postoperative chemotherapy should be started on the day of surgery or within 2 weeks after surgery. Or within 2 weeks after surgery. Each treatment course covers several cell proliferation cycles For the design of treatment cycle length, it is generally advocated that at least several cell proliferation cycles should be included. Experiments have proved that the efficacy of repeated application of anti-tumor drugs for 2-3 times in a value-added cycle is significantly enhanced. Tumor cells with short cycle time can be killed in large numbers and are relatively less toxic to normal cells, thus complete remission or even cure can be achieved. The doubling time of gastric cancer cells is about 40-60 days. The course of treatment for gastric cancer is generally considered reasonable to be given 6-10 times within 6-10 weeks. Combination chemotherapy In the combination chemotherapy regimen, two types of drugs with different mechanisms of action should be included in general, and often in the application of cycle non-specific drugs with cycle-specific drugs acting in different phases. The drugs should also be selected so that the toxicity of each drug does not overlap as much as possible to improve the tolerance of normal cells. The number of drugs generally advocates more than 2-3 drugs in combination is best. If the situation permits, it is possible to alternately apply two non-cross-resistant programs, which can better kill the tumor cells and even achieve the root of the cure. Make full use of the clinical trials of new drugs and new programs as well as molecular targeted drugs. The continuous emergence of newly developed chemotherapeutic drugs and molecular targeted drugs is undoubtedly a blessing for patients with advanced gastric cancer. For example, S-1 (Tegeo capsules) developed in Japan has achieved good efficacy since it was marketed in Japan in 2000, and is currently undergoing clinical trials in China. The clinical study on the effectiveness and safety of the combination of tegeo capsules + cisplatin for inoperable or recurrent metastatic advanced gastric cancer compares tegeo capsules alone, tegeo capsules combined with cisplatin and 5-FU combined with cisplatin for advanced gastric cancer in a multicenter, randomized, open, controlled clinical study. If there are patients with advanced gastric cancer can be actively enrolled, free examination and free medication during the treatment process, which reduces the financial burden of patients. At present, with the continuous emergence of molecular targeted drugs, the application of single-agent molecular targeted drugs and the combination of molecular targeted drugs and chemotherapy has become an important development direction for the treatment of advanced gastric cancer in the future. At present, our hospital has joined the clinical study led by the Cancer Hospital of Fudan University in Shanghai and the 81st Hospital of the Chinese People’s Liberation Army, namely the randomized double-blind, parallel-controlled, multi-center clinical study protocol of Apatinib Mesylate Tablets for the treatment of advanced gastric cancer, and patient treatment is under recruitment. It is foreseeable that in the coming years, the medical treatment of advanced gastric cancer will mainly rely on the combination of molecular targeted therapy drugs and chemotherapy to break the dilemma that the existing chemotherapy, no matter how it is composed, cannot bring greater survival benefit, but the combination of targeted therapy and chemotherapy may not revolutionize the progress if the current thinking is fixed. Therefore, there is a need to combine clinical and basic research, to do individualized treatment, to explore the feasibility of targeted therapy maintenance treatment, etc. In conclusion, some clinicians need to devote their efforts beyond the clinical routine to conduct in-depth research on the internal medicine treatment of gastric cancer.