GISTs can occur in all age groups, mostly between 40 and 70 years old, with a median age of 58 years. The incidence is slightly higher in men than in women. The mean age of our elderly subjects was 71.6 y. The clinical presentation of patients with GISTs varies widely and is usually nonspecific or even episodic. Symptoms may appear only when the tumor develops larger. Most patients develop symptoms when the tumor is more than 5 cm in diameter, including abdominal pain, abdominal masses, nausea, vomiting, anorexia, and weight loss. More than 40% of patients have acute bleeding into the intestine or abdominal cavity due to tumor rupture [2,4]. In our group, abdominal pain and gastrointestinal bleeding were non-specific symptoms in 62% (13/21) and 46% (10/21), respectively. Ren Hui, Department of Colorectal and Anorectal Surgery, Second Hospital of Jilin University
GISTs most often occur in the stomach (60%-70%) or small intestine (20%-30%), with less than 10% originating from the esophagus, colon, and rectum. gISTs can also occur in the extraintestinal, omental, mesenteric, and retroperitoneal cavities. deMatteo et al [4] reported 200 patients with GISTs, of which the stomach accounted for 39% and the small intestine for 32%. In our group, the stomach accounted for 57.1%, the esophagus for 33.3%, and the small intestine for 9.6% of the 21 cases, similar to those reported in the literature.
The results of this study showed that the main malignant indicators of GISTs were: nuclear schizophrenia ≥ 5/50 HPF, maximum tumor diameter ≥ 5 cm and infiltrative growth; reference indicators were: the presence of epithelial-like cell components, the presence of hemorrhage, necrosis, and cell heterogeneity and cell abundance; while interstitial mucinous degeneration, vitreous degeneration and inflammatory cell infiltration could occur in both benign and malignant, and were not meaningful for the diagnosis of benign and malignant The diagnosis of benign and malignant is not relevant. Benign and malignant are mainly determined by histological features, which is consistent with the report of Emory et al [3]. The results of this study also showed that malignant GISTs occur more commonly in the stomach and small intestine than in the esophagus, which may be related to the fact that GISTs in these sites are often larger in size, with a maximum diameter of 40 cm in the case of the posterior stomach in this study.
The diagnosis of GISTs is more difficult, with a low preoperative confirmation rate. GISTs are morphologically variable and difficult to differentiate from smooth muscle (sarcoma) and Chewang (sarcoma). With the use of immunohistochemistry and electron microscopy, clinical and pathologists are reconceptualizing GISTs. miettien et al [1] defined GISTs as tumors of mesenchymal origin of clostridial, epithelioid, or pleomorphic origin in cells of the gastrointestinal tract excluding smooth muscle tumors, nerve sheath tumors, and neurofibromas and expressing CD117. CD117 is the protein product of the c-kit proto-oncogene, a CD117 is the protein product of the c-kit proto-oncogene, a tyrosine kinase growth factor receptor and a member of the immunoglobulin superfamily. c-kit gene activation “switches” on and autophosphorylation ensues, activating the growth and survival of the relevant cells. Immunohistochemical studies have shown that GISTs express CD117, while smooth muscle tumors and nerve sheath tumors do not [5,6]. In this study, a group of antibodies such as CD117 and CD34 were used to label tumor cells, showing that elderly patients with GISTs showed positive expression of CD117, CD34, and VIM, while SMA and S-100 proteins were expressed in only one case each, reflecting that tumor cell antigen expression is related to the tissue type of the tumor itself. CD34 is a primitive hematopoietic tissue differentiation antigen, and the literature reports that CD34 is also highly expressed in CD117 is more sensitive than CD34. CD117 is highly sensitive and specific, and is a key indicator for diagnosis and differential diagnosis, and is the “gold standard” for GISTs [7]. Some GISTs express SMA and S-100 proteins, which are thought to characterize the tumor as smooth muscle or neural differentiation.
The immunophenotype mainly indicates the degree or direction of cell differentiation, and the immunostaining results are not related to the site, size, or cell density, and there is no proven relationship between them and the biological behavior of GISTs. There was no significant relationship between CD117, CD34, SMA and S-100 protein expression rates and either benign or malignant tumors in our data. Therefore, the immunophenotypic characteristics are not currently used as indicators for judging the benignity and malignancy of GISTs.
Surgical resection is the main method for the treatment of GISTs. The surgical approach is determined by tumor size, site and intraoperative frozen section results. Because GISTs, unlike adenocarcinoma of the gastrointestinal tract, rarely metastasize to the lymph nodes, the resection method is based on local excision, with the incision margin 2-3 cm from the tumor margin, and lymph node dissection is not necessary. In our group, only 3 cases were found to have local lymph node enlargement among 21 cases, and all of them were found to be reactive hyperplasia on pathological examination. If malignancy is suspected, the scope of resection should be enlarged, and if there is infiltration of surrounding organs, combined organ resection should be performed. In case of a single liver metastasis the corresponding liver segment can be resected and in case of lymph node metastasis a debulking procedure is performed. the largest related study conducted by DeMatteo et al [4] evaluated 200 patients with GISTs, 80 patients had complete resection of the primary disease and the 5-year disease-specific survival rate was 54%. Based on multifactorial analysis, relative tumor size (>10 cm) was the only negative influencing factor associated with disease-specific survival.
Radiotherapy has no significant role in the treatment of GISTs, and chemotherapy has not been reported to be effective. Oral Imatinib may be given to patients with malignant mesenchymal tumors or failure to resect and recurrence. Imatinib is a tyrosine kinase inhibitor with significant efficacy in patients with malignant GISTs expressing CD117. Croom et al [8] reported that 147 patients with advanced malignant mesenchymal tumors of the gastrointestinal tract treated with 400-600 mg of oral imatinib daily had an efficiency of 54% and a 1-year survival rate of 88%.
The prognosis of patients with malignant GISTs was mainly related to gender, tumor size and nuclear division index. Men, tumors ≥10 cm, and division indices ≥10/50 high-powered views have a poorer prognosis [9].