What is gastrointestinal mesenchymal tumor?
The concept of mesenchymal tumor was first introduced by Mazur and Clark in 1983. At first, it was not clearly understood as a tumor originating from mesenchymal connective tissue, and it was considered as a group with smooth muscle tumor and smooth muscle sarcoma. Gastrointestinal stromal tumors (GIST).
Who is the most common type of GIST?
GIST accounts for 1% to 3% of malignant tumors of the gastrointestinal tract and can occur in all age groups, mostly between 40 and 80 years old, with an average age of 60 years old and no significant difference in incidence between men and women.
What are the symptoms of GIST?
The most common clinical symptoms of GIST are upper abdominal discomfort, abdominal pain, and in some patients, a mass can be palpated in the abdomen. When the mucosa on the surface of the tumor breaks down, it can cause bleeding in the gastrointestinal tract, and when the tumor blood vessels are eroded, hemorrhage can occur, and patients may have symptoms such as vomiting blood and black stool.
How to find out if I have GIST?
Since GIST has no obvious specific symptoms, what tests can we use to find out if GIST is present? 1. Gastrointestinal endoscopy: Endoscopic GIST is characterized by submucosal hemispherical elevation, smooth mucosal surface, and may be accompanied by local erosion and ulceration. 2. Ultrasound endoscopy: It can clearly divide the gastrointestinal tract into different levels. size, growth direction and depth of infiltration, etc. If necessary, biopsy of the lesion can also be performed by puncture under ultrasound endoscopic guidance. Therefore, ultrasound endoscopy must be performed before treating GIST.3. Radiological examination: Enhanced CT and MRI are also diagnostic and assessment modalities for tumor extent, and can also detect the presence of liver and other distant metastases, cystic necrosis, etc., which are helpful in determining the benignity and malignancy of GIST.4. FDG-PET: It can comprehensively assess the systemic pathogenesis of tumor lesions and is considered to be the best choice to assess the early effect of targeted therapy for GIST, but it is not yet popularly used because of the high cost of the examination.
What are the characteristics of GIST tumors?
GIST tumors can vary in size, usually 2-6 cm in diameter, with grayish red or fish-like tissue sections, soft and brittle texture, necrohemorrhagic, mucinous or cystic changes in larger tumors, and relatively intact envelope.
What are the diseases that need to be differentiated from GIST? How is GIST diagnosed?
GIST has to be differentiated from other submucosal masses such as smooth muscle tumor, lipoma, carcinoid tumor, ectopic pancreas, etc. Besides relying on endoscopy, ultrasound endoscopy and CT, the gold standard for diagnosis is morphological examination (spindle cells or epithelioid cells) and immunohistochemical tests (positive for CD117, DOG-1, CD34). However, for a small number of patients with atypical GIST (negative for both CD117 and DOG-1), further genetic mutation testing is required according to the recommendations of the European Society of Medical Oncology (ESMO), which is important for the diagnosis of difficult GIST and for predicting the efficacy of targeted drugs.
How are GIST patients graded for risk?
Based on these indicators, in 2008, the National Institutes of Health (NIH) classified the risk level of GIST into four levels: very low risk, low risk, intermediate risk and high risk, with the higher the level, the higher the possibility of recurrence and metastasis.
Is gastrointestinal mesenchymal tumor a malignant tumor?
GIST is different from malignant tumors because they have different origins and different biological behaviors. gist is also less aggressive than malignant tumors, but gist is characterized by non-directional differentiation and potential malignancy. Because of its insidious onset and lack of typical clinical manifestations, GIST is difficult to detect early and easily missed or misdiagnosed. In recent years, with the further understanding of the pathogenesis of GIST and the rapid development of molecular biology and immunohistochemistry techniques, the level of diagnosis and treatment of this disease has been significantly improved.
How should GIST be treated after detection?
Since GIST is insensitive to radiotherapy and chemotherapy, the current treatment for GIST includes endoscopic treatment, combined endoscopic and laparoscopic double-laparoscopic treatment, laparoscopic surgery, open surgery and molecular targeted drug therapy. The traditional treatment in the past was mainly surgical resection, which required to strive for complete removal of the tumor as much as possible and achieve negative margins. While complete removal of the tumor, special attention should be paid to avoid tumor rupture and intraoperative dissemination, but open surgery is traumatic, painful and has a long hospital stay. However, laparoscopic surgery is less traumatic, and laparoscopic surgery has certain limitations, and it is difficult to locate small lesions (tumor diameter <2 cm) and some special parts of the tumor (such as intracavitary growth type or posterior gastric wall tumor), which is more difficult in operation. With the continuous development of endoscopic technology, endoscopic treatment of GIST has become possible and has shown its unique advantages. endoscopic submucosal mass excavation (ESE) can remove GIST with superficial growth site. for GIST with deep growth location and risk of endoscopic resection alone, the combination of gastroscopy and laparoscopy can achieve complementary advantages, which can not only remove the tumor completely, but also avoid open surgery. tumor, but also avoid open surgery, avoid excessive stomach wall and intestinal segment being removed, and maximize the protection of organ function. With the advantages of accurate localization, less trauma, fewer complications and less impact on organ function, the combined bimicroscopic technique is a new minimally invasive and effective method for the treatment of GIST. In addition, the newly emerged molecular targeted drugs such as imatinib and sunitinib can also play the role of inhibiting tumor growth by anti-angiogenesis and inhibiting tumor proliferation.
How long do molecularly targeted drugs need to be taken?
Imatinib is a selective tyrosine kinase inhibitor that exerts anti-tumor effects by inhibiting signaling pathways and tumor growth. It was approved by the FDA in 2002 to add a GIST indication and can be used for GIST patients who are preoperative, postoperative, or inoperable for other reasons. Since postoperative recurrence is common, surgical treatment alone is not enough. For patients with intermediate or high-risk GIST with risk of recurrence after surgical resection, they should all take oral molecular targeting drugs after surgery to prevent tumor recurrence and metastasis.
How to follow up GIST patients?
Follow-up after diagnosis of GIST should be done according to the risk level. Except for patients with very low-risk GIST who do not need follow-up, other patients, even after resection of the tumor, still need to be followed up. Since the most common sites of metastasis in GIST are the peritoneum and liver, enhanced CT or MRI of the abdomen and pelvis is a routine follow-up. Patients with recurrent metastases or unresectable GIST should be followed up every 3 months. For intermediate and high-risk patients, CT or MRI should be performed every 3 months for the first 3 years, and follow-up every 6 months in the fourth and fifth years. Patients with low-risk GIST should be followed up every 6 months until the 5th year.
In conclusion, GIST is the most common mesenchymal-derived tumor, and its diagnosis mainly relies on immunohistochemistry and cytology, endoscopic resection is currently the preferred treatment modality, and the invention and application of new molecular targeted drugs have significantly reduced GIST tumor recurrence and metastasis.