Diagnosis And Treatment Of Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors gastrointestinal stromal tumor(GIST) is a rare neoplasms. It was described to be a kind of leiomyoma of stomach, characteristic of round or polygonal cells by Stout in 1962. It was thought to be a special sort of leiomyoma-leiomyoblastoma or malignant leiomyoblastoma.In 1983,Mazur and Clark found that the GI mesenchymal tumors of the stomach, formerly defined as leiomyomas, lacked immunohistochemical features of Schwann cells and did not have ultrasturctural characteristics of smooth muscle cells through electronmicroscope and immunohistochemstry. Therefore, these authors used the histogenetically neutral designation GIST to name it when it was difficult to know its direction of differentiation.In 1998, great breakthrough of molecular studies was made.Hirota discovered the majority of GIST expressed c-kit protein KIT (CD117)which was related to the histogenesis and cell proliferation of GIST,and CD 117 is the characteristic of GIST. The definition of the GIST has changed greatly.Now GIST is in particular referred to the tumor with CD 117-positive and spindle cell and epithelioid cell of gastrointestinal mesenchymal tumors.With the intensive study of the pathology and immunohistochemistry, diagnosis rate has improved greatly.But for the lack of specific clinical manifestations,the preoperative diagnosis rate is still low,and the therapeutic schedule is not systematic as carcinoma of stomach, colon and rectum. In order to study the clinical features and therapeutic schedule,and improve the diagnostic or therapeutic efficacy,reduce the postoperative complications, we retrospectively analyze 40 cases of GIST diagnoised between January 2006 and Dcember 2008 in the second affiliated hospital of JILIN university(38 inpatients being operated).Among the 40 patients,the number of the male and female is equal(20 respectively).The mean age of them is 55.4 years-ranging from 32 to 77 years old.And the proportion of the patients under 50(30–50) is 30%,that under 70(50–70) is 55%,and that beyong 70 is 35%. First clinical presentations include epigastric discomfort (pain or abdominal distension) in 14 patients (35%), hypogastralgia in 6 patients(15.0%), changes of bowel habits in 4 patients(10.0%), abdominal mass in 3 patients(7.5%), hematemesis and melena in 3 patients(7.5%), and other ones are the discovery of physical examination, poor eating, fever, accident, vaginal bleeding, anal pain, nausea and vomiting and asthenia(25.0% in total). The signs are inclusive of abdominal tenderness in 33 patients, abdominal mass in 14 patients with the maximum gauge of 15cm , abnormality of rectal examination in 5 patients, peritonitis in 2 patients, and 2 patients without any signs.Under the endoscope, benign GIST is characeristic of hemispherical bulge, clear boundary, smooth mucosa and few ulcers, while the malignant GIST is featured of the large diameter, irregular cavity and deep ulcer, but with clear boundary. The endoscopy and biopsy is very important in preoperative diagnosis. Of all the 40 patients, 15 underwent the gastroscopy, 1 the enteroscopy, and 1 anoscopy. Endoscopic ultrasonography(EUS)can display the 5 layers of the gastric wall,and can be used to explore the origin, the volume, the boundry, the echos of the tumor. EUS is the most accurate method in diagonising the submucosal tumors.One patient underwent the EUS in this study. Under the ultrasonography,the tumor maybe solid or cystic,and some compartments in the cystic parts,and it is middle-echo or low-echo and closely related to the gastrointestinal tract. Ultrasonography has ben a routin inspection method beca- use it is inexpensive and availble easily. Of all the 40 patients, 15 underwent the ultrasonography.CT is an very important kind of examination,and it is much better than ultrasonography in the nature and location of tumor.Of the 40 patients,17 were inspected by CT,and the locations of tumors were as follows:4 in the hepatic region, 3 between stomach and pancreas, 2 between liver and stomach, 2 in the retinula region,and in the pelvic cavity, abdominal cavity, gastric region, duodenal region, right lower abdomen and cauda pancreatis for one patient respectively.The examination of pathology and immunohistochemistry is of very importance in the diagnosis of GIST, especially the immunohistochemistry which is the direct diagnostic evidence.The histocytologic patterns are various, but they often consist of two kins of cells:one-spindle cell and the other-epithelioid cell.CD117(c-kit) and CD 34 are the two very crucial markers in the immunohistochemistry.CD117 is expressed extensively in 81-100% GISTs, while CD34 in 56-82% GISTs. In our reseach, CD117 is expressed extensively in 92.5% GISTs, while CD34 in 82.5%, and this figure is in accord with the ones above.The standard therapy for GIST is still complete surgical resection. Whether the tumor is benign or malignant and the specific methods of operation are decided by the infiltration,the metastasis, the bulk and the intraoperative rapid pathologic checks. All the methods we did for the 38 patients were all decided by the factors discussed above. Among all the 38 tumors resected, 22 were in the stomach(10 were done by local resection, 10 by partial gastrectomy or rsubtotal gastrectomy, 2 by radical operation for carcinoma of stomach);9 were in the small intestine(by partial enterectomy);4 were in the rectum(3 were done by local resection, 1 refused to continue to treat);2 in the retroperitoneal (All were done by local resection); and 1 in the colon(It was done by by partial enterectomy.). There are maily two factors about the differnce in the principle of reatment between GIST and carcinoma of stomach, colon and rectum. One factor is that radiation treatment and chemotreatment about GIST is nearly invalid; the other one is that the molecular targeted drug Imatinib(Glive) is effective in treating GIST. But the Glive is so expensive that its application is limited.Conclusions: (1)GIST is a tumor having no sexual tendency, and it is lack of specific clinical manifestations. The familiar clinical presentations include bellyache, abdominal mass,hematemesis, melena and non-specific gastroin- testinal symptoms. (2)GIST is difficult to diagnose acurrately before operation. GIST should be considered if the nature of tumor is solid or cystic, especially the huge mass. (3)The methods of operations are decided by the infiltration, the metastasis, the bulk and the intraoperative rapid pathology. Its main method is local resection. (4) The standard therapy for GIST is still complete surgical resection. The radiation treatment and chemotreatment about GIST is nearly invalid. The promising molecular targeted drug Imatinib(Glive) is effective in treating GIST.