Gastrointestinal stromal tumor

　　Currently, the concept of mesenchymal tumors has shifted from being primarily smooth muscle tumors to primarily gastrointestinal stromal tumors. The occurrence of gastrointestinal stromal tumors is related to environmental factors and other factors.

　　1. Environmental factors:

　　Environmental factors are one of the more important factors in the production of gastric stromal tumors. The etiology of gastric stromal tumors is closely related to dietary habits in various places. Regular consumption of moldy, salted, smoked, and other foods, or excessive salt intake, may increase the risk of gastric stromal tumors. Smoked fish contains a lot of 3,4-benzopyrene, moldy food contains a lot of fungal toxins, and salted food contains nitrites, all of which have carcinogenic effects. Therefore, it is important to develop good living habits, refuse junk food, and eat more fruits and vegetables.

　　2. Environmental factors:

　　Research shows that the etiology of gastric stromal tumors is also related to genetics. The incidence of gastric stromal tumors in the families of patients is higher than that of the general population. These people may be due to similar living environments and dietary habits, which increase the risk of gastric stromal tumors. This also indicates that genetic factors play a relatively important role in the occurrence of gastric stromal tumors.

　　Gastrointestinal mesenchymal tumors account for only a small proportion of gastrointestinal tumors, but they are diverse in types, complex in morphology. In the past, due to the limitations of pathological techniques, many spindle cell tumors mixed with smooth muscle fibers or nerve bundles in the gastrointestinal tract were often diagnosed as smooth muscle-derived tumors or neurogenic tumors. Current research suggests that the majority of these are mesenchymal tumors similar to Cajal interstitial cells (Interstitial Cells of Cajal, ICC) that are positive for c-kit or CD34, which are currently defined as gastrointestinal stromal tumors. Smooth muscle-derived or neurogenic tumors only account for a very small proportion.

　　Gastrointestinal stromal tumors (GISTs) account for 1-3% of gastrointestinal malignant tumors, are more common in middle-aged and elderly patients, and are rare in patients under 40 years old. There is no significant difference in the incidence rate between men and women. Most GISTs occur in the stomach (50-70%) and small intestine (20-30%), with about 10-20% in the colon and rectum, 0-6% in the esophagus, and extremely rare in the mesentery, omentum, and retroperitoneum. About 20-30% of GIST patients are malignant, and approximately 11-47% have metastases at their first visit, mainly in the liver and peritoneum. Common complications of gastrointestinal stromal tumors include; the overall 5-year survival rate of GISTs is 35%, the 5-year survival rate after complete tumor resection is 50-65%, and the survival period for inoperable patients is less than 12 months. The tumor location, size, nuclear division number, and age are all related to the prognosis, with esophageal GISTs having the best prognosis and small intestinal GISTs having the worst.

　　Patients with gastrointestinal stromal tumors (GISTs) can prevent the risk factors for the onset of GISTs by paying attention to the following details of life and diet in daily life.

　　1, Strengthen physical exercise, enhance physical fitness, exercise more in the sun, and sweat more to expel acidic substances in the body through sweat, and avoid forming an acidic constitution.

　　2, Maintain a good attitude towards stress, combine work and rest, and do not overwork. It can be seen that stress is an important cause of cancer. Traditional Chinese medicine believes that stress leads to overwork and physical weakness, thereby causing a decrease in immune function, endocrine disorders, and internal metabolism disorders, leading to the deposition of acidic substances in the body; stress can also lead to mental tension, causing Qi stasis and blood stasis, and internal invasion of toxic fire.

　　3, Do not eat too much salty and spicy food, do not eat overheated, cold, expired, or deteriorated food; for the elderly, weak, or those with certain hereditary disease genes, eat some anti-cancer foods and alkaline foods with high alkaline content as appropriate, maintain a good mental state, develop good living habits, quit smoking, and limit alcohol intake. Smoking, according to the World Health Organization's prediction, if people stop smoking, the world's cancer rate will decrease by 1/3 after 5 years; secondly, do not drink excessively. Cigarettes and alcohol are highly acidic substances, and people who smoke and drink for a long time are prone to develop an acidic constitution. Discovering and treating diseases in a timely manner is the key.

　　CT, gastroscopy, endoscopic ultrasound examination, and gastrointestinal contrast examination can determine the size, local infiltration, metastasis, and location of GISTs (gastrointestinal stromal tumors), and the specific examination is as follows.

　　First, physical examination:Patients with larger tumors may feel abdominal active masses, smooth surface, nodules, or lobulated.

　　Second, laboratory examination:Patients may have anemia, hypoalbuminemia, and positive occult blood in feces.

　　Third, imaging characteristics:

　　1. Gastroscopy and endoscopic ultrasound examination

　　For gastric GIST, gastroscopy can help clarify the location and size of the tumor. Endoscopic ultrasound for extragastric tumors can assist in diagnosis, assist in the diagnosis of GIST location, size, origin, local infiltration, metastasis, etc. Some patients can obtain pathological diagnosis.

　　2. CT examination

　　CT plain scan shows that the tumor is mostly round or oval, a few are irregular. Benign tumors are often less than 5cm, with uniform density, sharp edges, and rarely invade adjacent organs, with calcification. Malignant tumors are often larger than 6cm, with unclear boundaries,粘连 with adjacent organs, may be lobulated, with uneven density, central necrosis, cystic degeneration and hemorrhage are easy to occur, the tumor may appear mixed high and low density, calcification is rare. Enhanced CT shows that uniform isodense ones often show uniform moderate or obvious enhancement, especially the spiral CT shows明显 in the venous phase. This enhancement pattern is more common in low-grade malignant gastrointestinal stromal tumors, and necrosis and cystic degeneration often show obvious peripheral enhancement. CT three-dimensional reconstruction of the digestive tract can assist in the diagnosis of the tumor, assist in the diagnosis of GIST location, size, local infiltration, metastasis, etc.

　　3. 18FDG-PET and 18FDG-PET/CT

      CT, MRI and other imaging methods can only evaluate the size, density and blood vessel distribution within the tumor, but cannot reflect the metabolic status of the tumor. PET examination with 18F-fluorodeoxyglucose can make up for the shortcomings of the above physical examination. Its principle is that gastrointestinal stromal tumors are highly metabolic tumors, which utilize the strong glycolysis reaction within the tumor to uptake high-density 18F-fluorodeoxyglucose for imaging. It is more sensitive to early metastasis or recurrence than CT, and is significantly superior to other physical examination methods in evaluating the response of the tumor to chemotherapy drugs. The PET and CT combined scanning method can simultaneously evaluate the anatomical and metabolic status of the tumor, which is superior to CT in tumor staging and the evaluation of treatment effect, and also provides a reference for the efficacy judgment of molecular targeted therapy for other solid tumors.

　　4. Other auxiliary examinations

　　X-ray barium meal shows regular edges, circular filling defects, central 'umbilical' ulcer shadow, or may be manifested as compression or displacement. Mesenteric artery DSA is of great significance for the diagnosis of small intestinal GIST and tumor localization.

      Gastrointestinal stromal tumors can alleviate symptoms in addition to general treatment methods, and dietary therapy can also help. The diet of patients with gastrointestinal stromal tumors should be light, and a reasonable diet should be arranged. It is necessary to have a balanced diet, eat more vegetables and fruits, and avoid spicy and刺激性 foods.

　　Traditional GIST (gastrointestinal stromal tumor) treatment is mainly surgical, although there have been significant advances in GIST pathology and basic research recently, and new chemotherapy drug research has also made certain progress, but surgical treatment is still the best method to achieve clinical cure at present.

　　1. Surgical treatment and principles

　　Due to the potential malignancy of GISTs, all clinical suspected GISTs should be operated on according to the principles of malignant tumor surgery. Since GISTs are often脆质，richly supplied with blood, and can metastasize through blood and peritoneum, special attention should be paid to avoid tumor rupture and compression during surgery, and the blood supply and return vessels of intestinal GISTs should be ligated first. Biopsy should not be taken from suspicious cases during surgery unless the tumor cannot be cured.

　　GISTs are generally not suitable for tumor resection, and GISTs with a diameter of 5cm in the stomach should be operated according to the D2 lymph node dissection range of gastric cancer. Small intestinal GISTs, due to the reported lymph node metastasis rate of 7-14%, it is recommended to perform routine lymph node dissection and resect the intestinal segment at least 10cm away from the tumor. For rectal GISTs, especially lower segment GISTs, surgical treatment may be very difficult, as it is difficult to judge the degree of malignancy before surgery. For those with a diameter of 5cm or recurrence after surgery, a choice should be made between preserving the anus and extensive surgery on the premise of fully consulting the patient's wishes before surgery. For those with local infiltration or distant metastasis, combined organ resection should be performed on the premise of radical resection.

　　2. Chemotherapy

　　Traditional chemotherapy treats GISTs as leiomyosarcomas, with the commonly used regimen being doxorubicin + cisplatin (AD regimen), with a clinical response rate

　　Imatinib (Imatinib) chemotherapy. Imatinib is a c-kit kinase inhibitor and was first applied clinically in 2000, mainly used for patients who cannot undergo curative surgery, and there are also reports of its use in high-risk GISTs. The application method is 400-800mg/day, for 12-24 months. According to phase II clinical studies, PR reached 63%, SD reached 20%; Phase III clinical studies are still lacking in long-term follow-up reports, but it is reported that the 6-month PFS exceeded 70%. Imatinib is also used in neoadjuvant chemotherapy for GISTs, and there are also small sample successful reports.