I. Surgical resection of IB-IVA postoperative radiotherapy for gastric cancer
When gastric cancer patients are diagnosed, most of them are locally advanced or have distant metastasis, and only about one-third of them have the chance of surgical resection. Especially for patients with locally advanced gastric cancer, even after surgical resection, local recurrence and distant metastasis are still high after surgery. Therefore, postoperative radiotherapy can improve patients’ prognosis by reducing the rate of local regional recurrence.
(i) Indications and radiotherapy dose
According to the radical degree of surgery, it is divided into R0, R1 and R2 resections. R0 means no residual tumor after surgery, R1 means microscopic residual tumor, and R2 means visual residual tumor. D0 means no lymph node dissection or incomplete lymph node dissection at station 1, D1 means complete lymph node dissection at station 1, D2 means complete lymph node dissection at station 2, D3 or D4 means lymph node dissection at station 3 or 4.
1.After R1 and R2 resection
Postoperative radiotherapy should be routinely performed. Dose of radiotherapy: 45~50Gy, 1.8~2Gy/time, five times a week. 45Gy followed by field reduction irradiation to 55~60Gy for the residual area of surgery.
2.After R0 resection
(1) After D0 or D1 resection, T2N0 patients can choose observation or postoperative radiotherapy. T3-4 or any T,N+ patients should undergo postoperative radiotherapy with a dose of 45Gy, 1.8-2Gy/dose, five times a week.
(2) After D2 resection, there is no definite conclusion whether postoperative radiotherapy is required. If radiotherapy is performed, the indications and radiotherapy dose are the same as (1).
(ii) Principles of simultaneous radiotherapy
If the patient is less than 75 years old; has a good general condition, KPS 370 score, life expectancy >6 months; has basically normal blood and liver and kidney functions; has no history of allergy to synchronous chemotherapy drugs; and can ensure daily energy intake >1500kcal, synchronous radiotherapy can be performed. There are fewer studies on postoperative radiotherapy alone, and some studies have failed to show that radiotherapy alone is more beneficial than surgery alone. Therefore, at present, postoperative radiotherapy for gastric cancer is based on simultaneous radiotherapy.
(iii) Chemotherapy regimen selection
1.5FU+CF (formyltetrahydrofolate): 5FU 400 mg/m2/day, LV 25 mg/m2/day, used 4 days before and 3 days after radiotherapy, intravenous drip.
2.Capecitabine (Siroda): 1600 mg/m2/day, administered orally twice daily (half an hour after meals) from the first day of radiotherapy to the last day of radiotherapy, with an interval of 12 hours between the two doses.
3.Tegeo (S-1): 80mg/m2/day, orally on the day of radiotherapy, without radiotherapy, orally twice a day (half an hour after meal), with an interval of 12 hours between two doses.
The initial studies of postoperative synchronous radiotherapy for gastric cancer were all based on 5FU as the synchronous chemotherapy regimen, but with the development of new chemotherapy drugs and the conclusion of clinical trials given, capecitabine is gradually replacing 5FU as the main drug for chemotherapy for gastrointestinal tumors with its lower toxic side effects and more convenient dosing.
(iv) Determination of the scope of 3D conformal radiotherapy (according to different TN stages, different radiotherapy scopes are determined)
CT examination should be routinely performed before radiotherapy, and PET-CT examination (localization) can be performed if available to help clarify the range of target area and whether there is distant metastasis (some distant metastatic lesions can be treated with radiotherapy at the same time as the primary site).
CTV includes GTV, tumor bed, anastomosis and regional lymphatic drainage area (the irradiated lymph node drainage area needs to be set according to different primary tumor locations, see Table 1); PTV is based on CTV, enlarged by 7mm in the left-right direction, 5mm in the anterior-posterior direction and 1cm in the head-foot direction.
2. According to the TN stage of the tumor and the primary location, the range of target area is different. Because the recurrence rate of residual stomach is low, and the target area including residual stomach will cause more intense radiotherapy response to patients, therefore, it is not recommended to include residual stomach.
(v) Protection of normal tissues and organs
The use of 3D-CRT or IMRT plan can better protect normal tissues and organs. For reference, the normal tissue and organ limits are as follows: spinal cord (PRV) ≤ 45 Gy; residual stomach V30 < 30% (no hot spots), liver V30 < 60%, kidney V20 < 30% on the side close to the target area; contralateral kidney V20 < 50%; small intestine V50 < 15% (no hot spots); postoperative pancreatic cancer patients should be limited to heart V30 < 30% and both lungs V20 < 20%. 20%.
(vi) Implementation of radiotherapy techniques
1. CT simulated localization: eat a small amount of food before localization, mix 20ml of 20% pantethine with 1000ml of water and take 800ml orally 1 hour before localization to visualize the small intestine. The remaining 200 ml was taken orally before the CT simulation scan to visualize the residual stomach, and the CT simulation scan was performed in the supine position with the hands on the forehead and the body membrane fixed. The scan range is from about 5 cm above the diaphragm to the level of umbilicus (in case of pancreatic cancer, the upper boundary of the scan should preferably be at the level of sternal angle) with a layer thickness of 5 mm. CT-enhanced scan is performed as much as possible to show the anatomical location more clearly, but if the patient is allergic to the contrast agent or due to advanced age or other serious underlying diseases, the enhanced scan may not be performed.
2. Try to apply 3D-CRT or IMRT plan with high-energy X-ray (≥6MV) irradiation; reduce the high volume points within the target area and limit each normal tissue and organ to the tolerable dose range.
3. IGRT can be used if available to ensure the accuracy of the treatment center; if the projection field radiographs are performed for verification, they should be taken at least once every two weeks. The daily radiotherapy time is fixed to avoid more the effect of feeding on the size of the residual stomach.
(vii) Pretreatment and symptomatic treatment of adverse reactions before and after treatment
Physical examination, assessment of toxic and side effects and routine blood tests should be performed once a week during treatment; if the routine blood results are abnormal, they should be rechecked every 2-3 days; liver and kidney functions should be rechecked once before, during and after treatment. Prevention and treatment of adverse reactions.
1. Treatment of nausea and vomiting, loss of appetite: 5-HT3 receptor blockers such as ondansetron, granisetron, toltesetron or gastroflucan, morpholine, etc. may be given orally with megestrol acetate to reduce side effects and enhance appetite.
2. Treatment of stomatitis: gargle with light salt water, oral Huasu tablets, local spraying of Jinin peptide or Jin Throat Jian; intravenous anti-inflammatory treatment and nutritional support if necessary.
3, swallowing pain or dysphagia treatment: Goldin peptide spray throat; can be combined with a small amount of local anesthetic mixture taken orally half an hour before meals; if necessary, intravenous nutritional support, can be combined with a small amount of hormone application.
4, reflux esophagitis and gastritis: Gastroflucan, morpholine, or cimetidine and other H2 receptor blockers, aluminum hydroxide and other antacids, aluminum thioglycollate and other gastric mucosa protectors, anti-inflammatory treatment if necessary.
5, diarrhea: oral simethicone and emmenagogue, etc. If dehydration occurs, intravenous anti-inflammatory therapy and nutritional support can be given according to the specific situation.
6, hand-foot syndrome: neurotrophic drug treatment, such as Vit B1, B12, etc..
7, skin reactions: topical treatment with Biopharm, goldin peptide, etc.
8, allergic reactions: discontinue the drug and give anti-allergic treatment.
9.Excessive weight loss: any cause of rapid or excessive weight loss, prompt intravenous nutritional support or nasal feeding is recommended.
10. hematological side effects: oral blood-raising drugs or subcutaneous injections of G-CSF, erythropoietin (EPO) or platelet-producing drugs (IL-11, TPO, etc.).
II. Preoperative synchronous radiotherapy for locally advanced inoperable resectable gastric cancer
The purpose of radiotherapy for inoperable resectable gastric cancer is to improve the surgical resection rate by shrinking the tumor, so as to improve the local control rate and long-term survival rate. CT, gastrointestinal imaging, gastroscopy and intracavitary ultrasound should be performed before treatment to clarify the lesion site and scope, and PET-CT examination (localization) is feasible if available.
(i) Indications and radiotherapy dose.
Patients with serious tumor local invasion or regional lymph node metastasis and estimated to be more difficult for surgery alone are suitable for preoperative simultaneous radiotherapy. In addition, patients of advanced age, poor cardiopulmonary function, combined with multiple underlying diseases and those who refuse surgery are also feasible for simple radiotherapy. If pyloric obstruction is severe, gastrointestinal short-circuit surgery is needed first to solve the outflow tract obstruction problem, and then radiotherapy can be administered to ensure the food and energy supply during radiotherapy.
Pre-operative radiotherapy dose: 45Gy, 1.8Gy/dose, five times a week. If the patient’s physical condition permits (the principle of synchronous radiotherapy is the same as that of postoperative synchronous radiotherapy), synchronous radiotherapy is recommended. The chemotherapy regimen is the same as that of postoperative synchronous radiotherapy. Radical radiotherapy: 45Gy followed by field reduction irradiation to the tumor area, with a supplemental dose to 55-60Gy.
(ii) Determination of the scope of 3D conformal radiotherapy (according to different TN stages, different radiotherapy scope is determined)
The target area should include the visually visible primary tumor (GTV) and metastatic regional lymph nodes (GTVnd) as determined by pre-treatment imaging data and the regional lymph node drainage area (CTV) requiring prophylactic irradiation, and the specific lymph node area for prophylactic irradiation is outlined in the target area of postoperative radiotherapy. the principles of PTV external radiation are the same as those of postoperative radiotherapy.
(iii) Protection of normal tissues and organs, implementation of radiotherapy techniques, pretreatment of adverse reactions before and after treatment and symptomatic treatment are all the same as postoperative simultaneous radiotherapy.
Radiation therapy for local recurrence of gastric cancer after surgery
Most of the patients with local recurrence of gastric cancer after surgery have lost the chance of second surgery, at this time, they can rely on radiotherapy. Radiotherapy can obviously relieve local symptoms of gastric cancer, such as pain and bleeding caused by gastric outflow tract obstruction and local tumor invasion, jaundice caused by metastatic lymph nodes pressing on bile duct, ascites or lower limb edema caused by pressing on inferior vena cava, thus relieving symptoms, improving life quality and prolonging survival. If simultaneous radiotherapy is used for some patients with better general condition, the treatment gain ratio may be increased.
Radiotherapy for postoperative recurrence of gastric cancer belongs to palliative radiotherapy, which should be done with involved field irradiation. The advantage of involved field irradiation is that the target area is relatively small, which can improve the radiotherapy dose to the local tumor area, while the radiotherapy response is relatively mild. The radiation therapy dose should be 50~60Gy, 1.8~2Gy/time, five times a week.