Indications of radiotherapy The main objectives of radiotherapy or radiochemotherapy for gastric cancer include preoperative or postoperative adjuvant treatment, palliative treatment and improvement of quality of life. Postoperative radiotherapy is mainly indicated for T3-4 or N+ (lymph node positive) gastric cancer; preoperative radiotherapy is mainly indicated for non-surgically resectable locally advanced or progressive gastric cancer; palliative radiotherapy is indicated for local recurrence and/or distant metastasis. (1) Postoperative synchronous radiotherapy is recommended for those who have radical gastric cancer (R0) with pathologic staging of T3-4 or positive lymph nodes (T3-4N+M0), if standard D2 surgery is not performed and preoperative radiotherapy is not performed; (2) Locally advanced non-operable resectable gastric cancer (T4NxM0), preoperative synchronous radiotherapy can be considered, and reevaluation can be made after the treatment, in order to strive for radical surgery; (3) Stage 1 gastric cancer (T4NxM0) with non-operable resection can be considered, with the treatment of T4NxM0, and reevaluation can be made after the treatment, in order to seek radical surgery; (3) Stage 2 gastric cancer Non-radical resection, patients with residual tumor (R1 or R2 resection), postoperative simultaneous radiotherapy is recommended; (4) Localized regional recurrence of gastric cancer, radiotherapy or radiochemotherapy is recommended; (5) Metastatic gastric cancer, such as relatively confined lesions, pain caused by bone metastases and brain metastases, palliative subtractive radiotherapy of tumor metastases or primary lesions is considered. Chemotherapy can be divided into palliative chemotherapy, adjuvant chemotherapy and neoadjuvant chemotherapy, which should be strictly controlled by clinical indications and administered under the guidance of medical oncologists. Chemotherapy should take into full consideration of the patient’s stage of illness, physical condition, adverse effects, quality of life and the patient’s wishes to avoid over- or under-treatment. The efficacy of chemotherapy should be evaluated in a timely manner, adverse effects should be closely monitored and prevented, and drugs and/or doses should be adjusted as appropriate. Evaluate the efficacy according to the efficacy evaluation criteria (Annex 5) or refer to the WHO solid tumor efficacy evaluation criteria. The evaluation criteria of adverse reactions should refer to NCI-CTC standards. 1. Palliative chemotherapy aims at relieving clinical symptoms caused by tumor, improving quality of life and prolonging survival. It is suitable for patients with unresectable, recurrent or palliative resection who are in good general condition and have normal function of major organs. Commonly used systemic chemotherapeutic agents include 5-fluorouracil (5-FU), capecitabine, tiglio, cisplatin, epoetinomycin, doxorubicin, paclitaxel, oxaliplatin, irinotecan, and so on. Chemotherapy regimen includes two-drug combination or three-drug combination regimen, two-drug regimen includes: 5-FU/LV + cisplatin (FP), capecitabine + cisplatin, tigio + cisplatin, capecitabine + oxaliplatin (XELOX), FOLFOX, capecitabine + paclitaxel, FOLFIRI and so on. Three-drug regimen is suitable for advanced gastric cancer patients with good physical condition, and commonly used regimens include ECF and its derivatives (EOX, ECX, EOF), DCF and its improved regimen. For patients with poor physical status and advanced age, single-agent chemotherapy with oral fluorouracil analogs or paclitaxel is considered. For advanced gastric cancer patients with positive HER-2 expression (++++ by immunohistochemical staining, or ++ by immunohistochemical staining and positive FISH test), the combined use of molecular targeted therapy drug trastuzumab on the basis of chemotherapy can be considered. 2. Adjuvant chemotherapy Adjuvant chemotherapy includes those with postoperative pathological stage Ib with lymph node metastasis and those with postoperative pathological stage II or above. Adjuvant chemotherapy starts when the patient’s physical condition is basically back to normal after surgery, and usually begins 3-4 weeks after surgery. Combination chemotherapy is completed within 6 months, and single-agent chemotherapy should not be used for more than 1 year. Adjuvant chemotherapy regimen recommended fluorouracil drugs combined with platinum two-drug combination program. For those with clinicopathologic stage Ib, poor physical condition, advanced age, and intolerance to two-drug combination regimen, single-agent chemotherapy with oral fluorouracil is considered. Neoadjuvant chemotherapy Neoadjuvant chemotherapy is recommended for locally progressive gastric cancer without distant metastasis (T3/4, N+), and a two-agent or three-agent combination chemotherapy regimen should be used, and single-agent application is not suitable. ECF and its modified regimen are recommended for neoadjuvant chemotherapy of gastric cancer. The time limit of neoadjuvant chemotherapy is usually not more than 3 months, and the efficacy should be evaluated in time and attention should be paid to determine the adverse reactions to avoid increasing surgical complications. Postoperative adjuvant therapy should be based on the preoperative stage and the efficacy of neoadjuvant chemotherapy; if it is effective, the original regimen should be continued or adjusted according to the patient’s tolerance; if it is ineffective, the regimen should be changed. Follow-up Gastric cancer patients should be followed up regularly by monitoring symptoms, signs and auxiliary examinations. The purpose of follow-up is to monitor the recurrence of disease or treatment-related adverse effects, and to evaluate the improvement of nutritional status. Follow-up should include hematology, imaging, endoscopy and other examinations. The frequency of follow-up visits should be every 3-6 months for 3 years, every 6 months for 3-5 years, and once a year after 5 years. Endoscopy was performed once a year. Vitamin B12 and folic acid should be supplemented for those who develop macrocytic anemia after total gastrectomy.