Two different mutational types of familial gastrointestinal stromal tumors:Two case reports

BACKGROUND Gastrointestinal stromal tumors(GISTs)are the most common mesenchymal tumors of the gastrointestinal(GI)tract,and cases of GISTs tend to be of the disseminated type,with a global incidence of 10 to 15 cases/million each year.The rarer familial GISTs,which often represent a population,differ in screening,diagnosis,and treatment.Familial GISTs include primary familial GISTs with predominantly KIT/PDGFRA mutations and wild-type GISTs.However,whether the same genetic family has different phenotypes has not been reported.CASE SUMMARY We report two cases of rare GISTs in the same family:A male patient with the V561D mutation in exon 12 of the PDGFRA gene,who has been taking the targeted drug imatinib since undergoing surgery,and a female patient diagnosed with wild-type GIST,who has been taking imatinib for 3 years since undergoing surgery.The favorable prognosis of these patients during the 7-year follow-up period validates the accuracy of our treatment strategy,and we have refined the entire process of diagnosis and treatment of familial GISTs in order to better manage this rare familial disease.CONCLUSION Different mutation types of familial GISTs in the same family are very rare,thus it is very important to make the correct diagnosis and treatment strategies according to the results of molecular detection for the management of familial GISTs.

Extragastrointestinal stromal tumors with diffuse membranous distribution with bleeding:A case report

BACKGROUND Extragastrointestinal stromal tumors(EGIST)and gastrointestinal stromal tumors are of similar pathological type and form.Here we report a rare case of EGIST diffusely distributed in membranous tissue in abdominal cavity,the feature of which included diffuse tumors at membranous tissue in entire abdominal cavity and spontaneous bleeding of the tumors.CASE SUMMARY The patient was a 71-year man and hospitalized due to continuous pain at lower abdomen for more than 10 days.Upon physical examination,the patient had flat and tough abdomen with mild pressing pain at lower abdomen,no obvious abdominal mass was touchable,and shifting dullness was positive.Positron emission tomography-computed tomography(CT)showed that in his peritoneal cavity,there were multiple nodules of various sizes,seroperitoneum,multiple enlarged lymph nodes in abdominal/pelvic cavity and right external ilium as well as pulmonary nodules.Plain CT scanning at epigastrium/hypogastrium/pelvic cavity+enhanced three-dimensional reconstruction revealed multiple soft tissue nodules in abdominal/pelvic cavity,peritoneum and right groin.Tumor marker of carbohydrate antigen 125 was 808 U/mL,diffuse tuberous tumor was seen in abdominal/pelvic cavity during operation with hematocelia,and postoperative pathological examination confirmed EGIST.Imatinib was administered with better therapeutic effect.CONCLUSION Gene testing showed breast cancer susceptibility gene 1 interacting protein C-terminal helicase 1 and KIT genovariation,and the patient was treated with imatinib follow-up visit found that his clinical symptoms disappeared and the tumor load alleviated obviously via imageological examination.

Insulin-like growth factor 2 targets IGF1R signaling transduction to facilitate metastasis and imatinib resistance in gastrointestinal stromal tumors

BACKGROUND Gastrointestinal stromal tumors(GISTs)are typical gastrointestinal tract neoplasms.Imatinib is the first-line therapy for GIST patients.Drug resistance limits the long-term effectiveness of imatinib.The regulatory effect of insulin-like growth factor 2(IGF2)has been confirmed in various cancers and is related to resistance to chemotherapy and a worse prognosis.AIM To further investigate the mechanism of IGF2 specific to GISTs.METHODS IGF2 was screened and analyzed using Gene Expression Omnibus(GEO:GSE225819)data.After IGF2 knockdown or overexpression by transfection,the phenotypes(proliferation,migration,invasion,apoptosis)of GIST cells were characterized by cell counting kit 8,Transwell,and flow cytometry assays.We used western blotting to evaluate pathway-associated and epithelial-mesenchymal transition(EMT)-associated proteins.We injected transfected cells into nude mice to establish a tumor xenograft model and observed the occurrence and metastasis of GIST.RESULTS Data from the GEO indicated that IGF2 expression is high in GISTs,associated with liver metastasis,and closely related to drug resistance.GIST cells with high expression of IGF2 had increased proliferation and migration,invasiveness and EMT.Knockdown of IGF2 significantly inhibited those activities.In addition,OEIGF2 promoted GIST metastasis in vivo in nude mice.IGF2 activated IGF1R signaling in GIST cells,and IGF2/IGF1R-mediated glycolysis was required for GIST with liver metastasis.GIST cells with IGF2 knockdown were sensitive to imatinib treatment when IGF2 overexpression significantly raised imatinib resistance.Moreover,2-deoxy-D-glucose(a glycolysis inhibitor)treatment reversed IGF2 overexpressionmediated imatinib resistance in GISTs.CONCLUSION IGF2 targeting of IGF1R signaling inhibited metastasis and decreased imatinib resistance by driving glycolysis in GISTs.

Systemic therapy in gastrointestinal stromal tumors

Gastrointestinal stromal tumors(GISTs)are the most common type of soft tissue sarcoma in the gastrointestinal tract.Most GISTs have been attributed to activated gain-of-function mutations in either KIT or platelet-derived growth factor receptorα,making these molecular features essential targets for therapeutic interventions.Although surgery is the standard treatment for localized GISTs,patients often experience relapse and disease progression even after surgery.In recent years,targeted therapy has significantly improved the prognosis of patients with advanced GISTs.Imatinib mesylate,a KIT inhibitor,is the first-line treatment for advanced GISTs and has revolutionized the treatment of this disease.However,drug resistance remains a major issue with imatinib treatment,as a significant majority of patients become resistant to imatinib either after initiation or after 2–3 years of treatment.Consequently,novel tyrosine kinase inhibitors such as sunitinib,regorafenib,ripretinib,and avapritinib have been introduced to address drug resistance.Immunotherapy has emerged as a potential approach for the treatment of advanced GISTs.This review comprehensively summarizes the pathogenesis of GISTs and the development of targeted therapies and immunotherapies,provides an overview of the emergence of drug resistance in advanced GISTs,and discusses the challenges and prospects associated with the treatment of GISTs.

Gastric IgG4-related disease mimicking a gastrointestinal stromal tumor in a child: A case report

BACKGROUND Gastric IgG4-related disease(IgG4-RD)is rarely encountered in clinical practice,and especially more so among pediatric patients.To our knowledge,this is the first report of IgG4-RD presenting as a calcifying gastric mass in a child.We describe how this entity was difficult to differentiate from a gastrointestinal stromal tumor(GIST)imaging-based approaches.Therefore,this case highlights the importance of considering IgG4-RD in the differential diagnosis of gastric tumor before performing surgical resection,especially to distinguish it from malignancy to avoid unnecessary surgery.CASE SUMMARY The patient suffered from epigastric pain for several days.Panendoscopy and computed tomography scan revealed a submucosal tumor.Differential diagnoses included GIST,leiomyoma,teratoma,and mucinous adenocarcinoma.However,laparoscopic proximal gastrectomy allowed for the definitive diagnosis of IgG4-related stomach disease.CONCLUSION We emphasize the importance of considering IgG4-RD in the differential diagnosis of gastric submucosal tumors before performing surgical resection.

Effect and safety of ripretinib in the treatment of advanced gastrointestinal stromal tumor:A systematic review and metaanalysis

BACKGROUND Imatinib(IMA)has received approval as the primary treatment for gastrointestinal stromal tumors(GIST).Nonetheless,approximately half of the patients with advanced GIST show disease advancement following IMA treatment.Presently,the efficacy of secondary and tertiary medications in addressing various GIST secondary mutations is somewhat restricted.Consequently,there is a significant medical demand for the creation of kinase inhibitors that extensively block secondary drug-resistant mutations in advanced GIST.Ripretinib(RPT)is a new,switch-control tyrosine kinase inhibitors that can suppress different mutations of KIT and PDGFRA via a dual mechanism of action.AIM To investigate the literature on RPT to assess an effective,safe,and successful treatment strategy against advanced GIST.METHODS The present systematic review and meta-analysis was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.PubMed,Embase,Cochrane,Web of Science and ClinicalTrials.gov databases were screened from January 1,2003 to May 1,2024.RESULTS A total of 4 studies were included,with a total of 507 patients enrolled.The objective response rate(ORR)of the RPT-treated advanced GIST was 17%(95%CI:0.11-0.27),while the disease control rate(DCR)was 66%(95%CI:0.59-0.73).The overall occurrence of adverse events with varying degrees was 97%(95%CI:0.93-1),whereas that of grade≥3 adverse reactions was 42%(95%CI:0.28-0.63).The sensitivity analysis revealed that omitting some studies did not yield statistically notable variances in the aggregate data regarding the ORR,DCR,and the occurrence of adverse events of grade 3 or higher.The publication bias was absent because no significant asymmetry was observed in Begg’s funnel plot in all studies.CONCLUSION RPT has favorable efficacy profiles in GIST patients,but the adverse reactions are obvious,and patient management needs to be strengthened to achieve better safety and tolerability.

Advancing gastrointestinal stromal tumor management: The role of imagomics features in precision risk assessment

BACKGROUND Gastrointestinal stromal tumors(GISTs)vary widely in prognosis,and traditional pathological assessments often lack precision in risk stratification.Advanced imaging techniques,especially magnetic resonance imaging(MRI),offer potential improvements.This study investigates how MRI imagomics can enhance risk assessment and support personalized treatment for GIST patients.AIM To assess the effectiveness of MRI imagomics in improving GIST risk stratification,addressing the limitations of traditional pathological assessments.METHODS Analyzed clinical and MRI data from 132 GIST patients,categorizing them by tumor specifics and dividing into risk groups.Employed dimension reduction for optimal imagomics feature selection from diffusion-weighted imaging(DWI),T1-weighted imaging(T1WI),and contrast enhanced T1WI with fat saturation(CET1WI)fat suppress(fs)sequences.RESULTS Age,lesion diameter,and mitotic figures significantly correlated with GIST risk,with DWI sequence features like sphericity and regional entropy showing high predictive accuracy.The combined T1WI and CE-T1WI fs model had the best predictive efficacy.In the test group,the DWI sequence model demonstrated an area under the curve(AUC)value of 0.960 with a sensitivity of 80.0%and a specificity of 100.0%.On the other hand,the combined performance of the T1WI and CE-T1WI fs models in the test group was the most robust,exhibiting an AUC value of 0.834,a sensitivity of 70.4%,and a specificity of 85.2%.CONCLUSION MRI imagomics,particularly DWI and combined T1WI/CE-T1WI fs models,significantly enhance GIST risk stratification,supporting precise preoperative patient assessment and personalized treatment plans.The clinical implications are profound,enabling more accurate surgical strategy formulation and optimized treatment selection,thereby improving patient outcomes.Future research should focus on multicenter studies to validate these findings,integrate advanced imaging technologies like PET/MRI,and incorporate genetic factors to achieve a more comprehensive risk assessment.

Relationship between multi-slice computed tomography features and pathological risk stratification assessment in gastric gastrointestinal stromal tumors

BACKGROUND Computed tomography(CT)imaging features are associated with risk stratification of gastric gastrointestinal stromal tumors(GISTs).AIM To determine the multi-slice CT imaging features for predicting risk stratification in patients with primary gastric GISTs.METHODS The clinicopathological and CT imaging data for 147 patients with histologically confirmed primary gastric GISTs were retrospectively analyzed.All patients had received dynamic contrast-enhanced CT(CECT)followed by surgical resection.According to the modified National Institutes of Health criteria,147 lesions were classified into the low malignant potential group(very low and low risk;101 lesions)and high malignant potential group(medium and high-risk;46 lesions).The association between malignant potential and CT characteristic features(including tumor location,size,growth pattern,contour,ulceration,cystic degeneration or necrosis,calcification within the tumor,lymphadenopathy,enhancement patterns,unenhanced CT and CECT attenuation value,and enhancement degree)was analyzed using univariate analysis.Multivariate logistic regression analysis was performed to identify significant predictors of high malignant potential.The receiver operating curve(ROC)was used to evaluate the predictive value of tumor size and the multinomial logistic regression model for risk classification.RESULTS There were 46 patients with high malignant potential and 101 with low-malignant potential gastric GISTs.Univariate analysis showed no significant differences in age,gender,tumor location,calcification,unenhanced CT and CECT attenuation values,and enhancement degree between the two groups(P>0.05).However,a significant difference was observed in tumor size(3.14±0.94 vs 6.63±3.26 cm,P<0.001)between the low-grade and high-grade groups.The univariate analysis further revealed that CT imaging features,including tumor contours,lesion growth patterns,ulceration,cystic degeneration or necrosis,lymphadenopathy,and contrast enhancement patterns,were associated with risk stratification(P<0.05).According to binary logistic regression analysis,tumor size[P<0.001;odds ratio(OR)=26.448;95%confidence interval(CI):4.854-144.099)],contours(P=0.028;OR=7.750;95%CI:1.253-47.955),and mixed growth pattern(P=0.046;OR=4.740;95%CI:1.029-21.828)were independent predictors for risk stratification of gastric GISTs.ROC curve analysis for the multinomial logistic regression model and tumor size to differentiate high-malignant potential from low-malignant potential GISTs achieved a maximum area under the curve of 0.919(95%CI:0.863-0.975)and 0.940(95%CI:0.893-0.986),respectively.The tumor size cutoff value between the low and high malignant potential groups was 4.05 cm,and the sensitivity and specificity were 93.5%and 84.2%,respectively.CONCLUSION CT features,including tumor size,growth patterns,and lesion contours,were predictors of malignant potential for primary gastric GISTs.

Optical second-harmonic generation imaging for identifying gastrointestinal stromal tumors

Gastrointestinal stromal tumors(GISTs)are the most common mesenchymal tumors arising in the digest tract.It brings a challenge to diagnosis because it is asymptomatic clinically.It is well known that tumor development is often accompanied by the changes in the morphology of collagen fibers.Nowadays,an emerging optical imaging technique,second-harmonic generation(SHG),can directly identify collagen fibers without staining due to its noncentrosymmetric properties.Therefore,in this study,we attempt to assess the feasibility of SHG imaging for detecting GISTs by monitoring the morphological changes of collagen fibers in tumor microenvironment.We found that collagen alterations occurred obviously in the GISTs by comparing with normal tissues,and furthermore,two morphological features from SHG images were extracted to quantitatively assess the morphological difference of collagen fibers between normal muscular layer and GISTs by means of automated image analysis.Quantitative analyses show a significant difference in the two collagen features.This study demonstrates the potential of SHG imaging as an adjunctive diagnostic tool for label-free identification of GISTs.

Neurofibromatosis type 1 with multiple gastrointestinal stromal tumors:A case report

BACKGROUND Neurofibromatosis type 1(NF1)is characterized by café-au-lait patches on the skin and the presence of neurofibromas.Gastrointestinal stromal tumor(GIST)is the most common non-neurological tumor in NF1 patients.In NF1-associated GIST,KIT and PDGFRA mutations are frequently absent and imatinib is ineffective.Surgical resection is first-line treatment.CASE SUMMARY A 56-year-old woman with NF1 was hospitalized because of an incidental pelvic mass.Physical examination was notable for multiple café-au-lait patches and numerous subcutaneous soft nodular masses of the skin of the head,face,trunk,and limbs.Her abdomen was soft and nontender.No masses were palpated.Digital rectal examination was unremarkable.Abdominal computed tomography was suspicious for GIST or solitary fibrous tumor.Laparoscopy was performed,which identified eight well-demarcated masses in the jejunum.All were resected and pathologically diagnosed as GISTs.The patient was discharged on day 7 after surgery without complications.No tumor recurrence was evident at the 6-mo follow-up.CONCLUSION Laparoscopy is effective for both diagnosis and treatment of NF1-associated GIST.

Sunitinib-induced hyperammonemic encephalopathy in metastatic gastrointestinal stromal tumors:A case report

BACKGROUND Sunitinib,a multi-targeted tyrosine kinase inhibitor(TKI),has been approved for the salvage treatment of gastrointestinal stromal tumors(GIST).Hyperammonemic encephalopathy is a rare but severe complication of sunitinib use.Here,we present the case of a 66-year-old male with metastatic GIST without underlying liver cirrhosis who developed sunitinib-induced hyperammonemic encephalopathy.CASE SUMMARY A 66-year-old male with metastatic GIST was admitted because of reduced consciousness.Imatinib was administered as the first-line systemic therapy.He experienced repeated episodes of peritonitis due to tumor perforation,and surgery was performed.Progressive disease was confirmed based on increased liver metastasis,and sunitinib was initiated as a salvage treatment.However,23 d after the third course of sunitinib,he presented to the emergency room with an episode of altered consciousness and behavioral changes.Based on the patient clinical history and examination findings,sunitinib-induced encephalopathy was suspected.Sunitinib was discontinued,and the patient was treated for hyperammonemia.The patient had a normal level of consciousness four days later,and the serum ammonia level gradually decreased.No further neurological symptoms were reported in subsequent follow-ups.CONCLUSION TKI-induced hyperammonemic encephalopathy is potentially life-threatening.Patients receiving TKIs experiencing adverse reactions should undergo systemic evaluation and prompt treatment.

GASTROINTESTINAL STROMAL TUMORS OF THE ANORECTUM——A SPECIAL ENTITY: GISTs OF THE ANORECTUM

Objective： Until recently gastrointestinal stromal tumor （GIST） has been separated from other mesenchymal neoplasms and categorized as a special entity. Morphology of tumor cells and immunohistochemical findings with CD117 are crucial in the pathological diagnosis of GISTs. Newly developed drug imatinib mesylate （formerly called STI571） has been proved effective for GISTs. The distinction of GISTs and other mesenchymal tumors has great clinical significance, especially for lesions located in the anorectum. Methods： The authors searched the database of Peking University, School of Ontology for patients with anorectal neoplasms treated from January 1995 to June 2002. Information of 12 patients with anorectal mesenchymal tumors was collected. The patients were reevaluated and discussed according to current criteria of GISTs with clinical data and immunohistochemical findings. Results： Six patients （including 3 males） were finally diagnosed as anorectal GISTs. The median age of those patients was 59.5 years （27～69）. The symptoms were not specific. Three cases with original diagnosis of leiomyoma or leiomyosarcoma were actually GISTs. A total of six anorectal GISTs was found comprising about 1.06% of patients with anorectal neoplasmas in the same period. Besides CD117, CD34 and vimentin were also expressed in majority of these patients. Five of the six patients underwent surgical resection one of which received neoadjuvant chemotherapy before resection Conclusion： Anorectal GISTs should be considered as a special entity using current diagnostic criteria. Surgical resection remains the primary therapeutic strategy. Neoadjuvant imatinib mesylate may be helpful in sphincter-sparing operations and improvement of the quality of life for these patients.

Gastrointestinal Stromal Tumors (GISTs), Surgical Management and Clinical Outcome

Introduction: This study investigated the incidence, surgical management and outcome of Gastrointestinal Stromal Tumors (GIST) in Upper Egypt. Methods: A retrospective review of all GIST patients admitted a South Egypt Cancer Institute between Jan. 2010 and Dec. 2015 was conducted. Patients’ demographics, clinical presentation, tumor characteristics, radiological, pathological and immunohistochemical findings, surgical procedures, recurrence and mortality were recorded. Results: A total of 36 GIST patients were identified, stomach was the most common site (27.8%) followed by the small intestine (19.4%) and the large intestine (16.7%). The mean age at time of diagnosis as 52.8 ± 14.4 (ranged from 17 to 76 years). Of these 36 cases, 20 (55.6%) cases were males and 16 (44.4%) cases were females with a ratio of 1.2:1. About 22 cases (61.1%) presented with primary tumors, eight cases (22.2%) had primary tumors and metastases, three cases (8.35) presented with recurrent mass, whereas one case (2.2%) presented either with recurrent mass and metastases or metastases only. The majority of cases (22) had tumorsize >5 cm. Patients were stratified as high, intermediate, low and very low risk (50.6%, 30.6%, 11.1% and 2.8%, respectively). Almost all the cases were surgically managed and 75% were completely resectable. During follow up (average 26.5 months), 22 patients showed complete recovery, 7 had recurrent or metastatic disease and 2 died due to liver metastasis. Conclusion: The incidence of GIST in Upper Egypt is apparently low. Surgical resection is the preferred choice of treatment. The demographic data of GIST patients in South Egypt Cancer institute were similar to those published in the literature. Other prospective studies are required to assess the prognosis and the effect of treatment.

Management Colorectal Gastrointestinal Stromal Tumors (Gists) in Surabaya

Introduction: Colorectal gastrointestinal stromal tumors (GISTs) mesenchymal tumor is very uncommon. GISTs effect mostly on the stomach and small intestine and rarely occur in the colon, rectum and esophagus, that originating from precursors of the interstitial cells that originate of Cajal. The symptoms of gastrointestinal stromal tumor depend on the site and size of the tumor, and may include abdominal pain, gastrointestinal bleeding or signs of obstruction;small tumors may, however, be asymptomatic. Some of the patients with gastrointestinal stromal tumor have bloody stools, obstruction and abdominal pain as the commonest manifestation. Immunocytochemical staining for CD117 is helpful in confirming the diagnosis. Case presentation: We report 3 new cases of GISTs: two occurred at the rectal and the other at descending Colon. Two cases are over 50 years of age and, and all cases the chief complain of bowel obstruction, abdominal pain in two cases, and one case with anemia and urine retention. All the patients were operated and were permormed pathology examinatiom. All case ware positive result for immunocytochemical staining CD117. All cases we had presented had size more than 5 cm are considered as unfavorable prognostic factors to Fletcher criteria, all patients scheduled for chemotherapy with Glivec but just one patient continued to used Glivec. Post surgery follows up one patient post milles with urinary incontinence complaints found and that patients are trained to CIC (intermittent catheterization). Conclusion: Colorectal gastrointestinal stromal tumors are very rare and can present as mass abdomen. Resection and chemotherapy are the treatment of choice.

TATA-box-binding protein-associated factor 15 is a novel biomarker that promotes cell proliferation and migration in gastrointestinal stromal tumor

BACKGROUND Gastrointestinal stromal tumor(GIST)is a common neoplasm with high rates of recurrence and metastasis,and its therapeutic efficacy is still not ideal.There is an unmet need to find new molecular therapeutic targets for GIST.TATA-boxbinding protein-associated factor 15(TAF15)contributes to the progress of various tumors,while the role and molecular mechanism of TAF15 in GIST progression are still unknown.AIM To explore new molecular therapeutic targets for GIST and understand the biological role and underlying mechanisms of TAF15 in GIST progression.METHODS Proteomic analysis was performed to explore the differentially expressed proteins in GIST.Western blotting and immunohistochemical analysis were used to verify the expression level of TAF15 in GIST tissues and cell lines.Cell counting kit-8,colony formation,wound-healing and transwell assay were executed to detect the ability of TAF15 on cell proliferation,migration and invasion.A xenograft mouse model was applied to explore the role of TAF15 in the progression of GIST.Western blotting was used to detect the phosphorylation level and total level of RAF1,MEK and ERK1/2.RESULTS A total of 1669 proteins were identified as differentially expressed proteins with 762 upregulated and 907 downregulated in GIST.TAF15 was selected for the further study because of its important role in cell proliferation and migration.TAF15 was significantly over expressed in GIST tissues and cell lines.Overexpression of TAF15 was associated with larger tumor size and higher risk stage of GIST.TAF15 knockdown significantly inhibited the cell proliferation and migration of GIST in vitro and suppressed tumor growth in vivo.Moreover,the inhibition of TAF15 expression significantly decreased the phosphorylation level of RAF1,MEK and ERK1/2 in GIST cells and xenograft tissues,while the total RAF1,MEK and ERK1/2 had no significant change.CONCLUSION TAF15 is over expressed in GIST tissues and cell lines.Overexpression of TAF15 was associated with a poor prognosis of GIST patients.TAF15 promotes cell proliferation and migration in GIST via the activation of the RAF1/MEK/ERK signaling pathway.Thus,TAF15 is expected to be a novel latent molecular biomarker or therapeutic target of GIST.

Rectal gastrointestinal stromal tumors:Imaging features with clinical and pathological correlation

AIM:To investigate computed tomography(CT) and magnetic resonance imaging(MRI) manifestations of rectal gastrointestinal stromal tumors(GISTs) in order to enhance the recognition of these rare tumors.METHODS:Fourteen patients with pathologically proven rectal GISTs were retrospectively reviewed.Patient histories were retrospectively reviewed for patient age,gender,presenting symptoms,endoscopic investigations,operation notes and pathologic slides.All tumors were evaluated for CD117,CD34 expression,and the tumors were stratified according to current criteria of the National Institutes of Health(NIH).In all cases the first pre-operation imaging findings(CT and MRI,n = 3;MRI only,n = 8;CT only,n = 3) were analyzed by two experienced radiologists by consensus,which include:tumor size,shape,CT density(hypodense,isodense and hyperdense),MRI signal intensity(hypointense,isointense and hyperintense),epicenter(intraluminal or extraluminal),margin(well-defined or ill-defined),internal component(presence of calcifications,necrosis,hemorrhage or ulceration),pattern and degree of enhancement,invasion into adjacent structures.After review of the radiologic studies,clinical and pathological findings were correlated with radiological findings.RESULTS:The patients,13 men and 1 woman,were aged 31-62 years(mean = 51.5 ± 10.7 years).The most common initial presentation was hematochezia(n = 6).The mean tumor diameter was 5.68 ± 2.64 cm(range 1.5-11.2 cm).Eight lesions were round or oval,and 6 lesions were irregular.Eleven lesions were welldefined and 3 had ill-defined margins.Ten tumors were extraluminal and 4 were intraluminal.The density and MR signal intensity of the solid component of the lesions were similar to that of muscle on unenhanced CT(n = 6) and T1-weighted images(n = 11),and hyperintense on T2-weighted MR images.Calcification was detected in 2 tumors.Following intravenous injection of contrast media,3 lesions had mild enhancement and 11 lesions had moderate enhancement.Enhancement was homogenous in 3 lesions and heterogeneous in 11.In 1 of 11 patients who underwent both CT and MRI,the tumor was homogenous on CT scan and heterogeneous on MRI.Eight patients were classified as high risk according to the modified recurrent risk classification system of NIH.CONCLUSION:Rectal GISTs usually manifest as large,well-circumscribed,exophytic masses with moderate and heterogeneous enhancement on CT and MRI.The invasion of adjacent organs,bowel obstruction and local adenopathy are uncommon.

A gist of gastrointestinal stromal tumors: A review

Gastrointestinal stromal tumors (GISTs) have been recognized as a biologically distinctive tumor type, different from smooth muscle and neural tumors of the gastrointestinal tract (GIT). They constitute the majority of gastrointestinal mesenchymal tumors of the GIT and are known to be refractory to conventional chemotherapy or radiation. They are defined and diagnosed by the expression of a proto-oncogene protein detected by immunohistochemistry which serves as a crucial diagnostic and therapeutic target. The identification of these mutations has resulted in a better understanding of their oncogenic mechanisms. The remarkable antitumor effects of the molecular inhibitor imatinib have necessitated accurate diagnosis of GIST and their distinction from other gastrointestinal mes-enchymal tumors. Both traditional and minimally invasive surgery are used to remove these tumors with minimal morbidity and excellent perioperative outcomes. The revolutionary use of specific, molecularlytargeted therapies, such as imatinib mesylate, reduces the frequency of disease recurrence when used as an adjuvant following complete resection. Neoadjuvant treatment with these agents appears to stabilize disease in the majority of patients and may reduce the extent of surgical resection required for subsequent complete tumor removal. The important interplay between the molecular genetics of GIST and responses to targeted therapeutics serves as a model for the study of targeted therapies in other solid tumors. This review summarizes our current knowledge and recent advances regarding the histogenesis, pathology, molecular biology, the basis for the novel targeted cancer therapy and current evidence based management of these unique tumors.

Molecular basis and management of gastrointestinal stromal tumors

Molecularly targeted agents have dramatically impacted the management of several cancers. Targeting KIT has led to a new treatment paradigm in gastrointestinal stromal tumors (GISTs). KIT is a cell surface receptor with tyrosine kinases that, upon binding of its ligand, stem cell factor, activates various signaling pathways. Imatinib and sunitinib, both tyrosine kinase inhibitors directed to KIT, were approved for firstand secondline treatment of metastatic and unresectable GISTs. In this article, we will review the molecular pathogenesis of GISTs followed by a discussion of imatinib and sunitinib’s role in the treatment of GISTs. Finally, we will introduce novel therapeutic options for imatiniband sunitinib-resistant GISTs.

Role of Ki-67 as a prognostic factor in gastrointestinal stromal tumors

AIM:To investigate primarily the prognostic value of Ki-67,as well as other parameters,in gastrointestinal stromal tumors(GISTs).METHODS:Ki-67,c-KIT,platelet-derived growth factor receptor-alpha(PDGFRα),smooth muscle actin(SMA),CD34,S100 were stained for immunohistochemistry which was performed on formalin-fixed,paraffinembeded sections on representative block from each case.Proliferation index counted by Ki-67 antibody was calculated as a number of positive nuclear reaction over 100 cells.Immunoreactivity for c-KIT and PDGFRα was evaluated semiquantitatively(weak,intermediate,strong) and for c-KIT type of reactivity was analyzed(cytoplasmic,membrane and "dot-like" staining).Immunoreactivity for SMA,CD34 and S100 were was evaluated as positive or negative antigen expression.Pathologic parameters investigated in this study included tumor size,cell type(pure spindle,pured epitheloid mixed spindle and epitheloid),mitotic count,hemorrhage,necrosis,mucosal ulceration.Clinical data included age,gender,primary tumor location and spread of disease.χ 2 test and Student's t-test were used for comparisons of baseline characteristics.The Cox's proportional hazard model was used for univariable and multivariable analyses.Survival rates were calculated by Kaplan-Meier method and statistical significance was determined by the log-rank test.RESULTS:According to the stage of disease,there were 36 patients with localized disease,29 patients with initially localized disease but with its recurrence in the period of follow up,and finally,35 patients had metastatic disease from the very beginning of disease.Tumor originated most commonly in the stomach(41%),small intestine was the second most common location(36%).The mean size of primary tumors was 6.5 cm.The mean duration of follow-up was 60 mo.Multiple parameters were analyzed for their effect on overall survival,but no one reached statistical significance(P = 0.06).Analysis of time to progression/relapse in initially localized disease(univariate analysis),tumor size,mitotic count,Ki-67 and type of d-KIT distribution(cytoplasmic vs membrane/"dot-like") showed statistically significant correlation.In multivariate analysis in the group of patients with localized disease,there were only 2 parameters that have impact on relapse,Ki-67 and SMA(P < 0.0001 and P < 0.034,respectively).Furthermore,Ki-67 was analyzed in localized diseasevs localized with recurrence and metastatic disease.It was shown that there is a strict difference between these 2 groups of patients(median value was 2.5 for localized disease vs 10.0 for recurrent/metastatic disease,P < 0.0001).It was also shown that the cut-off value which is still statistically significant in terms of relapse on the level of 6%.The curves for survival on that cut-off level are significantly different(P < 0.04,Cox F).CONCLUSION:Ki-67 presents a significant prognostic factor for GIST recurrence which could be of great importance in evaluating malignant potential of disease.

Prognostic angiogenic markers(endoglin, VEGF, CD31) and tumor cell proliferation(Ki67) for gastrointestinal stromal tumors

AIM: To evaluate the correlation between the immunoexpression of angiogenic markers [CD31, CD105 and vascular endothelial growth factor(VEGF)], proliferative index(Ki67), and prognosis of patients with gastrointestinal stromal tumors(GIST).METHODS: This is a retrospective study of 54 GIST cases. Medical records were searched to obtain the GIST patients' demographic and clinical data, and paraffin-embedded blocks of tumor samples were retrieved from the hospital archives to conduct a new immunohistochemical evaluation. The tumor samples of GIST patients were subject to immunohistochemical evaluation for endoglin(CD105), CD31, VEGF, and Ki67 expression. The CD105 and CD31 intratumoral microvascular density(IMVD) was measured using automated analysis. We determined the correlation between the immunoexpression of CD105, CD31, VEGF,Ki67 and prognosis. In addition, we conducted a cutoff analysis using the receiver-operating characteristic curve. VEGF positivity was classified as either null/weak or strong. Ki67 was evaluated using a cutoff of 5%positive cells. The prognosis was classified as good(patient alive without recurrence) or poor(patient with recurrence/death).RESULTS: The distribution of tumor sites among the54 analyzed samples was as follows: 27(50%) in the stomach, 20(37.1%) in the small intestine, 6(11.1%)in the colon, and 1(1.8%) in the esophagus. The size of the tumors ranged from 2 to 33 cm(median: 8cm); in 12 cases(22.2%), the tumor was below 5 cm at the largest diameter, but in 42 cases(77.7%), the tumor was larger than 5 cm. The means of CD105 and CD31 were significantly higher in the group with poor prognosis(P < 0.001). The cut-off values of CD105(>1.2%) and CD31(> 2.5%) in the receiver-operating characteristic curve were related to a poorer prognosis.Cases with a better prognosis showed significantly null/weak staining for VEGF(P < 0.001). Ki-67 expression of≥ 5% was strongly correlated with a worse prognosis(P< 0.001). In the multivariate analysis, CD105 was the variable that most strongly correlated with prognosis.CONCLUSION: The IMVD cutoff values for the angiogenic markers CD105 and CD31, may be prognostic factors for GIST, in addition to VEGF and Ki67.