Diagnosis of gastrointestinal stromal tumors: a consensus approach

Pathology of gastrointestinal stromal tumors

Gastrointestinal stromal tumor (GIST) is a well recognized and relatively well understood soft tissue tumor. Early events in GIST development are activating mutations in KIT or PDGFRA, which occur in most GISTs and encode for mutated tyrosine receptor kinases that are therapeutic targets for tyrosine kinase inhibitors, including imatinib and sunitinib. A small minority of GISTs possessing neither KIT nor PDGFRA mutations may have germline mutations in SDH, suggesting a potential role of SDH in the pathogenesis. Immunohistochemical detection of KIT, and more recently DOG1, has proven to be reliable and useful in the diagnosis of GISTs. Because current and future therapies depend on pathologists, it is important that they recognize KIT-negative GISTs, GISTs in specific clinical contexts, GISTs with unusual morphology, and GISTs after treatment. This review focuses on recent developments in the understanding of the biology, immunohistochemical diagnosis, the role of molecular analysis, and risk assessment of GISTs.

Expression of podoplanin is a rare event in sporadic gastrointestinal stromal tumors and does not influence prognosis

Aims: Podoplanin overexpression is associated with worse prognosis in several human cancers. In gastrointestinal stromal tumors (GISTs) very few data on the expression of podoplanin exist, but it seems to be frequently overexpressed in pediatric/syndromic GISTs. We investigated podoplanin expression and its clinical relevance in a large series of sporadic GISTs. Methods: Podoplanin expression was determined immunohistochemically in 145 sporadic adult GISTs. Aneuploidies of 1p36 and 1q25 were investigated using FISH, and KIT and PDGFRA genes were investigated by sequencing. Results: Overexpression of podoplanin was observed in eight (5.6%) GISTs and no association with amplification of 1p36 or KIT or PDGFRA mutations was seen. The amount of podoplanin expression was not associated with clinical risk factors or patient survival. Conclusion: Overexpression of podoplanin is a rare event in sporadic GISTs and is not associated with amplification of 1p36 or with KIT or PDGFRA mutations, which indicates limited pathobiological or clinical relevance.

Occurrence of Comorbidities before and after Soft Tissue Sarcoma Diagnosis

Background. Data is limited on the burden of common comorbidities, such as cardiovascular disease (CVD), respiratory disease and diabetes, or comorbidities related to cancer and its treatment, such as anemia and depression, in patients with soft tissue sarcoma (STS). Patients and Methods. From the Dutch Pathology Registry linked to the PHARMO database (including data on drug use and hospitalizations), 533 patients with STS were selected during 2000–2007 and matched 1 : 10 to cancer-free controls. The occurrences of comorbidities were assessed in the 12 months before and after STS diagnosis. Results. STS patients were 2–4 times more likely to have comorbidities at diagnosis compared with cancer-free controls. The incidence of CVD, anemia, and depression after STS diagnosis differed significantly from cancer-free controls and decreased during followup from 40–124 per 1,000 person-years (py) during the first six months to 11–38 per 1,000 py more than 12 months after diagnosis. The incidence of respiratory disease and diabetes among STS patients remained stable during followup (5–21 per 1,000 py) and did not differ significantly from cancer-free controls. Conclusions. STS patients were more likely to have comorbidities before cancer diagnosis and to develop CVD, anemia, and depression after diagnosis compared to cancer-free controls.

Current management of gastrointestinal stromal tumors--a comprehensive review

BACKGROUND

Gastrointestinal stromal tumors (GISTs) comprise < 1% of all gastrointestinal (GI) tumors, but GISTs are the most common mesenchymal tumors of the GI tract. Dramatic changes in clinical practice have been observed in the last decade. This review highlights the overall management of GIST and its recent developments.

METHOD

We identified literature by searching Medline and PubMed from January 1995 to December 2011 using the keywords "gastrointestinal stromal tumors", "GIST", "imatinib" and "tyrosine kinase inhibitor". Additional papers were identified by a manual search of the references from the key articles. There were no exclusion criteria for published information to the topics.

RESULTS

For localized primary GISTs, surgical resection is the mainstay of therapy. The 5-year survival rate after complete resection of GISTs is approximately 50%-65%. Many factors including tumor size, mitotic rate, tumor location, kinase mutational status and occurrence of tumor rupture have been extensively studied and proposed to be predictors of survival outcomes. Adjuvant imatinib is proposed as an option for those patients with a substantial risk of relapse. Unresectable metastatic or recurrent GIST can be treated with a tyrosine kinase inhibitor, imatinib, with a remarkable response (50%-70%) and prolonged survival (median progression-free survival: 18-20 months; median overall survival: 51-57 months). The standard approach in the case of tumor progression on 400 mg once per day is to increase the imatinib dose to 400 mg twice per day as permitted by toxicity. Use of a second-line targeted agent, sunitinib, in patients with advanced GIST who fail (or are intolerant of) imatinib therapy is advised.

CONCLUSION

Treatment for GISTs has become increasingly complex because of the growing understanding of its biology. A multidisciplinary team that includes radiologists, medical oncologists, pathologists, and surgeons is paramount for the effective treatment of GIST.

Safety and efficacy of image-guided percutaneous biopsies in the diagnosis of gastrointestinal stromal tumors

BACKGROUND

After the invention of effective target agent therapy for gastrointestinal stromal tumors (GISTs), percutaneous biopsies may be indicated for unresectable diseases or before neoadjuvant chemotherapy. The purpose of this study was to evaluate the safety and efficacy of percutaneous biopsies for GISTs.

MATERIAL AND METHODS

Fifty-eight procedures of transluminal biopsies or image-guided percutaneous biopsies in 49 patients at our Institution from 1999 to 2010 were retrospectively reviewed.

RESULT

Twenty-three transluminal biopsies, 20 ultrasonography-guided biopsies, and 15 CT-guided biopsies were performed. Failure rate was higher in the group of transluminal biopsies (17%). There is no major procedure-related complication in patients who underwent percutaneous biopsy. However, life-threatening bleeding after transluminal biopsies happened in two patients.

CONCLUSION

Image-guided percutaneous biopsy is a safe and efficient alternative tool for the diagnosis of patients with GISTs.

Endoscopic management of gastrointestinal stromal tumors

Subepithelial lesions are increasingly being identified with improved endoscopic imaging technologies. Many of these lesions are now recognized as gastrointestinal stromal tumors (GISTs). Recent advances in immunohistochemistry have allowed for reliable differentiation of GISTs from other subepithelial tumors, thereby significantly improving our understanding of these lesions. The wealth of recent information and continual evolution in our understanding of GISTs has exposed some knowledge gaps pertaining to the optimal management of these lesions. In this article, we review the endoscopic management of GISTs as it relates to the identification, diagnosis and management of these lesions based on the best available literature and our own clinical experience to date.

Endoscopic submucosal dissection for treatment of gastric subepithelial tumors (with video)

BACKGROUND

Endoscopic submucosal dissection (ESD) is a well-accepted method for removing superficial mucosal tumors; however, there is limited data on the use of this method for removing subepithelial tumors.

OBJECTIVE

To investigate the efficacy, safety, and outcome of ESD for gastric subepithelial tumors and determine factors related to treatment success.

DESIGN

Retrospective analysis of a prospectively maintained database.

SETTING

Single tertiary academic center.

PATIENTS AND INTERVENTIONS

From April 2007 to November 2010, 37 patients with gastric subepithelial tumors were treated with ESD.

MAIN OUTCOME MEASUREMENTS

Macroscopically and microscopically complete en block resection rate (R0), complication rate, and endosonographic features predictive of R0 resection.

RESULTS

The median tumor diameter was 25.0 mm, (range 10-60 mm, IQR 17-37). The overall rate of R0 resections was 81.1% (30/37, 95%CI: 61.8-90.2%), including 100% (15/15, 95%CI: 78.2-100.0%) of tumors from the submucosa and 68.2% (15/22, 95%CI: 45.1-86.1%) of tumors from the muscularis propria. Seventeen patients had a final diagnosis of gastrointestinal stromal tumor. The severe complication (perforation) rate was 5.4% (2/37, 95%CI: 0.0-9.5%). One patient required surgery; the other was treated conservatively. No recurrence was observed in patients with R0 resections at a median follow up of 21.0 months (IQR 11-35). Successful R0 resections were predicted by the observation of no, or only narrow, tumor connections with the underlying muscle layer during EUS (OR=35.0, 95%CI: 3.7-334.4, p=0.001).

LIMITATIONS

Single-center, retrospective analysis, short follow-up.

CONCLUSIONS

ESD is an effective and relatively safe method for removing gastric subepithelial tumors. Endoscopic ultrasonography findings can predict complete tumor resections.

A gentleman with an unusual cause of hypoalbuminemia

Protein-losing enteropathy (PLE) is a rare syndrome of gastrointestinal protein loss that may complicate a variety of diseases. The primary causes can be divided into erosive gastrointestinal disorders, nonerosive gastrointestinal disorders, and disorders involving increased central venous pressure or mesenteric lymphatic obstruction.

Herein, we report on a 65-year-old man with PLE caused by invasive gastrointestinal stromal tumor (GIST). To our best knowledge, this is the first reported association between GIST and PLE. A brief review of the literature on the incidence, pathogenesis and management of GIST is also presented.

Gastrointestinal stromal tumors

INTRODUCTION

The gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the intestinal tract, known to be refractory to conventional chemotherapy or radiation. Its pathogenesis is defined by mutations within the KIT and PDGFRA gene, which constitutively activate KIT and PDGFRA oncoproteins, and serve as crucial diagnostic and therapeutic targets.

DISCUSSION

Besides surgery, therapy with imatinib mesylate, which inhibits KIT kinase activity, represents the other cornerstone for the treatment of GIST. Still, the only curative option for GIST is given after complete surgical removal even in a metastatic setting, but recurrence is common, and the risk can be defined by surgical factors like incomplete resection, intraperitoneal rupture, or bleeding and tumor associated factors like tumor size, mitotic index, or localization.

CONCLUSION

Consequently, adjuvant therapy with imatinib mesylate or other tyrosine kinase inhibitors is recommended for high-risk patients after complete resection. For unresectable and advanced GIST, a partial response or stable disease can be achieved in about 80% of patients with imatinib mesylate.

Extragastrointestinal Stromal Tumor (EGIST) in the abdominal wall: Case report and literature review

INTRODUCTION

Gastro Intestinal Stromal Tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract (GI). GIST that arises primarily outside the GI tract is termed Extragastrointestinal Stromal Tumor (EGIST). To the best of our knowledge, few cases of EGIST in the abdominal wall were reported.

PRESENTATION OF CASE

We present a rare case of EGIST in the abdominal wall of a 57 year-old female patient. The asymptomatic tumor was located in the superior aspect of the left rectus abdominis muscle, measured 5.4 × cm 5.3 × cm 6.9 cm and was well circumscribed. Histological examination showed an epithelioid cell morphology. The mitotic count was 7/50 HPFs. Immunohistochemistry showed diffuse strong CD117 positivity, focal positivity for S100. The tumor was excised and the margins were free of malignancy. The patient was doing well postoperatively and was discharged on STI-571 regimen.

DISCUSSION

Although GIST is the most common mesenchymal tumor of the gastrointestinal tract, a case with EGIST in the abdominal wall is rare. Positive immunohistochemical staining for CD117 is a defining feature of GISTs. A great percentage of EGISTs represent a metastasis from a primary GIST. In our case, the clinical and diagnostic work-up have been proved it to be an EGIST.

CONCLUSION

The existing data on EGIST is insufficient to make a final conclusion regarding the malignant potential and clinicopathological factors of EGISTs that determine patient prognosis. Thus a follow-up for a long period is required. EGISTs should be kept in mind in the differential diagnosis for patients presenting with solid mass of the abdominal wall.

An essential role of PDCD4 in progression and malignant proliferation of gastrointestinal stromal tumors

Programmed cell death 4 (PDCD4) is a tumor suppressor that can inhibit tumorigenesis by suppressing activator protein (AP)-1 activation and protein translation. Lost or decreased PDCD4 expression has been found in multiple types of human cancers, which was also associated with progression and metastasis of the tumors. However, the status and significance of PDCD4 in gastrointestinal stromal tumors have not been evaluated. In the present study, we examined the PDCD4 expression in a total of 63 gastrointestinal stromal tumor samples at both mRNA and protein levels by RT-PCR, western blot, and immunohistochemistry. We demonstrated that the expression of PDCD4 mRNA was diminished in 68% (17/25) of the tumor samples, and the level of PDCD4 protein appeared to be decreased in 66.7% (42/63) of the samples, as compared to adjacent normal gastrointestinal tissues, which expressed high levels of PDCD4 mRNA and protein. In addition, altered expression of PDCD4 was associated with clinicopathological parameters including risk group, tumor size, and mitosis. Moreover, PDCD4 expression had a negative correlation with the Ki-67 labeling index (r = -0.6059, P < 0.0001). All these results suggest that downregulation of PDCD4 expression may have an essential role in the progression and malignant proliferation of human gastrointestinal stromal tumors.

Application of ultrasonography in the diagnosis and treatment of gastric stromal tumors

Gastric stromal tumors are common mesenchymal tumors of the gastrointestinal tract. Common clinical manifestations include abdominal pain, bowel obstruction, gastrointestinal bleeding, and abdominal mass. Gastric stromal tumors show a histological feature of spontaneous differentiation. Ultrasound examination plays an important role in the diagnosis and treatment of gastric stromal tumors. Here we review the application of ultrasonography in the diagnosis and treatment of gastric stromal tumors.

Two out of three required: a case of incomplete Carney triad

A 48-year-old woman presented with chest symptoms. Multiple lesions seen on chest imaging were found to be pulmonary chondromas following surgical resection. Whole body magnetic resonance scan performed to investigate the possibility of Carney triad demonstrated a gastric lesion. This was resected and found to be a gastrointestinal stromal tumor. No evidence of paragangliomata was found on imaging. A diagnosis of incomplete Carney triad was made. Carney triad is a rare multiple neoplastic association of pulmonary chondroma, gastrointestinal stromal tumor, and paraganglioma. At least 2 tumors are required for diagnosis. Most patients are young women. No genetic cause has been identified. Management involves surgical resection of tumors and follow-up for recurrence and investigation for other elements of the triad.

Local resection by combined laparoendoscopic surgery for duodenal gastrointestinal stromal tumor

Combined laparoendoscopic surgery is a novel surgical method which consists of both endoscopic surgery from inside the gastrointestinal tract and laparoscopic surgery from the outside. We report a case of duodenal GIST, in which combined laparoendoscopic local resection was attempted. The lesion was resected endoscopically using endoscopic submucosal dissection technique under laparoscopic assistance. Laparoscope was used for originating the orientation of the tumor, intra-operative EUS, and monitoring serosal injury from the peritoneal cavity. Postoperative hemorrhage occurred; however, precise orientation of the lesion helped us to manage the patient with minimal invasive reoperation. And thus, the bowel integrity was completely preserved, by avoiding segmental duodenal resection and pancreaticoduodenectomy. This novel, less invasive surgical procedure may become an attractive option for the lesions originating in the anatomically challenging portion of the GI tract for endoscopic or laparoscopic surgery alone.

Gastric schwannomas show an obviously increased fluorodeoxyglucose uptake in positron emission tomography: report of two cases

Schwannomas are tumors originating from any nerve that has a Schwann cell sheath. Gastrointestinal (GI) schwannomas represent only 3% of all GI mesenchymal tumors. The stomach is the most common site of GI schwannomas, and schwannomas account for 0.2% of all gastric neoplasms. This report presents two cases of gastric schwannomas showing increased [18F]fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET; maximum standardized uptake value 7.10 and 6.05). Additional immunohistochemical staining of glucose transporter type 1 (GLUT1) and the autocrine motility factor (AMF) was conducted after the tumors were resected, to identify the mechanism that increased FDG uptake on PET. Immunohistochemical expression of AMF was positive in both cases, whereas GLUT1 was negative. Autocrine motility factor is also known as phosphoglucose isomerase. However, the mechanism by which FDG is accumulated in schwannoma cells is uncertain, and may be related to intracellular glycolytic activity.

Use of balloon enteroscopy in preoperative diagnosis of neurofibromatosis-associated gastrointestinal stromal tumours of the small bowel: a case report

Neurofibromatosis type I (NF1) is one of the most common inheritable disorders and is associated with an increased risk of gastrointestinal stromal tumours (GISTs). However, the predominant location of these lesions in the small bowel makes them difficult to diagnose. We report the successful use of balloon enteroscopy in conjunction with conventional methods for clinical diagnosis of jejunal GISTs in a 70-year-old man with NF1 who presented with melaena. The importance of screening NF1 patients for GISTs and the complementary role of balloon enteroscopy with capsule endoscopy in such diagnoses is discussed.

Circulating levels of cell adhesion molecule L1 as a prognostic marker in gastrointestinal stromal tumor patients

BACKGROUND

L1 cell adhesion molecule (CD171) is expressed in many malignant tumors and its expression correlates with unfavourable outcome. It thus represents a target for tumor diagnosis and therapy. An earlier study conducted by our group identified L1 expression levels in primary gastrointestinal stromal tumors (GIST) as a prognostic marker. The aim of the current study was to compare L1 serum levels of GIST patients with those of healthy controls and to determine whether levels of soluble L1 in sera could serve as a prognostic marker.

METHODS

Using a sensitive enzyme-linked immunosorbent assay (ELISA), soluble L1 was measured in sera of 93 GIST patients und 151 healthy controls. Soluble L1 levels were then correlated with clinicopathological data.

RESULTS

Median levels of soluble L1 were significantly higher (p < 0.001; Mann-Whitney U test) in sera of GIST patients compared to healthy individuals. Median soluble L1 levels were particularly elevated in patients with recurrence and relapse (p < 0.05; Mann Whitney U test).

CONCLUSION

These results suggest that high soluble L1 levels predict poor prognosis and may thus be a promising tumor marker that can contribute to individualise therapy.

Unusual features of gastrointestinal stromal tumor on PET/CT and CT imaging

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. It can be benign or malignant in behavior. Stomach, being the most common site (70%) for GISTs, is followed by the small intestine (20%). Anorectal, colonic, and esophageal GISTs are uncommon, whereas extraintestinal GISTs are extremely rare. The presenting symptoms are highly dependent on tumor size and location, although a large number of GISTs are asymptomatic. The purpose of this article is to highlight the unusual characteristics of GISTs illustrated by PET/CT and CT imaging. These characteristics are organized into (1) unusual tumor location, (2) unusual clinical presentation, and (3) unusual sites of metastasis. Knowing the uncommon features of GISTs is important, as they are more often seen nowadays with the increasingly important role of PET/CT and CT in GIST management; and these tumors are associated with a poorer prognosis and unwanted delay in diagnosis is avoidable. With the availability of effective treatment by imatinib mesylate, a prompt and early diagnosis is essential for disease control. All GISTs illustrated in this article are pathologically proven.

Microarray analysis identifies versican and CD9 as potent prognostic markers in gastric gastrointestinal stromal tumors

Although the main cause of gastrointestinal stromal tumor (GIST) is gain-of-function mutations in the c-kit gene in the interstitial cells of Cajal, concomitant genetic or epigenetic changes other than c-kit appear to occur in the development of metastasis. We sought to identify the genes involved in the metastatic process of gastric GIST. Microarray analysis was performed to compare gene expressions between three gastric GIST and four metastatic liver GIST. Expression levels were higher for 165 genes and lower for 146 genes in metastatic liver GIST. The upregulation of five oncogenes and downregulation of four tumor suppressor genes including versican and CD9 were confirmed by quantitative reverse transcriptional PCR. Immunohistochemistry in 117 GIST revealed that protein levels of versican and CD9 were higher and lower, respectively, in metastatic GIST. High expression of versican and low expression of CD9 in 104 primary gastric GIST correlated with poor disease-free survival (P = 0.0078 and P = 0.0018). In addition to the c-kit gene mutation, genetic or epigenetic changes other than c-kit play important roles in the metastatic process. In particular, versican and CD9 are potential prognostic markers in gastric GIST.

Hypervascular subepithelial gastrointestinal masses: CT-pathologic correlation

Although the vast majority of gastrointestinal (GI) masses are epithelial neoplasms, a variety of subepithelial masses are infrequently encountered during endoscopic or radiologic examination. A subepithelial mass, which was previously called a submucosal mass, is defined as a mass covered with normal-appearing mucosa, whether the underlying process is intramural or extramural in origin. At contrast material-enhanced computed tomography (CT), hypervascular subepithelial masses are usually detected more easily than isoattenuating or hypovascular masses. Entities that appear as intramural hypervascular subepithelial lesions include neuroendocrine tumors, GI stromal tumor, glomus tumor, hemangioma, angiosarcoma, Kaposi sarcoma, nerve sheath tumors, hypervascular metastases, heterotopic tissues, and vascular structures. Entities that appear as extramural hypervascular subepithelial lesions include Castleman disease, solitary fibrous tumor, inflammatory myofibroblastic tumor, and actinomycosis. Some rare gastric cancers resemble subepithelial tumors. In comparison with endoscopic ultrasonography, CT is of limited value in differentiating the layers of the GI wall and determining the origin of mass lesions. However, recent advances in multidetector CT with multiplanar reformation allow one to determine whether a GI mass is of epithelial, intramural subepithelial, or extramural subepithelial origin. Furthermore, the full extent of tumors can be delineated, and local invasion and distant metastases can be identified. Familiarity with the characteristic CT appearances of hypervascular subepithelial masses of the GI tract will help radiologists make a more confident diagnosis.

Neurotensin receptor 1 is expressed in gastrointestinal stromal tumors but not in interstitial cells of Cajal

Gastrointestinal stromal tumors (GIST) are thought to derive from the interstitial cells of Cajal (ICC) or an ICC precursor. Oncogenic mutations of the KIT or PDGFRA receptor tyrosine kinases are present in the majority of GIST, leading to ligand-independent activation of the intracellular signal transduction pathways. We previously investigated the gene expression profile in the murine Kit^K641E GIST model and identified Ntsr1 mRNA, encoding the Neurotensin receptor 1, amongst the upregulated genes. Here we characterized Ntsr1 mRNA and protein expression in the murine Kit^K641E GIST model and in tissue microarrays of human GIST. Ntsr1 mRNA upregulation in Kit^K641E animals was confirmed by quantitative PCR. Ntsr1 immunoreactivity was not detected in the Kit positive ICC of WT mice, but was present in the Kit positive hyperplasia of Kit^K641E mice. In the normal human gut, NTSR1 immunoreactivity was detected in myenteric neurons but not in KIT positive ICC. Two independent tissue microarrays, including a total of 97 GIST, revealed NTSR1 immunoreactivity in all specimens, including the KIT negative GIST with PDGFRA mutation. NTSR1 immunoreactivity exhibited nuclear, cytoplasmic or mixed patterns, which might relate to variable levels of NTSR1 activation. As studies using radio-labeled NTSR1 ligand analogues for whole body tumor imaging and for targeted therapeutic interventions have already been reported, this study opens new perspectives for similar approaches in GIST.

Role of endoscopic ultrasonography in the diagnosis and treatment of smooth esophageal protuberant lesions

AIM: To investigate the role of endoscopic ultrasonography (EUS) in the diagnosis and treatment of smooth esophageal protuberant lesions.

METHODS: Three hundred and thirty patients with smooth esophageal protuberant lesions were examined by EUS. Of these patients, 100 were treated by endoscopic mucosal resection (EMR), 8 by loop ligature, and 7 by surgery.

RESULTS: Endoscopic treatment was successful at one time in all cases, and the success rate was 100%. Postoperative pathology revealed leiomyoma in 94 cases, interstitialoma in three cases, cavernous hemangioma in one case, granular cell tumor in one case, and cyst in one case. The coincidence rate between endoscopic ultrasonography and pathology was 94%. No major complications such as hemorrhage and perforation occurred. No recurrence or metastasis occurred during 2-24-month follow-up.

CONCLUSION: EUS has high value in the diagnosis and treatment of smooth esophageal protuberant lesions.

Quantitative functional imaging by dynamic contrast enhanced ultrasonography (DCE-US) in GIST patients treated with masatinib

OBJECTIVES

To determine the quantitative parameters of DCE-US for predicting early functional response of patients with metastatic gastrointestinal stromal tumors (GIST).

MATERIALS AND METHODS

Phase II multicentre clinical trial in patients with metastatic GIST treated with masatinib mesylate (7.5 mg/kg daily by oral route) Patients followed using three different imaging techniques: 1) DCE-US before treatment and on days 1, 7, 15 and after 1, 2, 4, 6 months and every 3 months. 2) CT assessments, using RECIST criteria, before treatment, after 2, 4, 6 months and then every 3 months. 3) FDG PET before treatment and after 1 month.

RESULTS

Twenty patients included and followed-up for up to 36 months, with 269 DCE-US examinations performed. No significant changes in the 7 selected DCE-US variables on day 1 and 7 vs baseline. On day 15, significant reductions in all the variables related to blood volume recorded: area under the curve (AUC) (p = 0. 004), area under the wash-in (AUWI) (p = 0.002), area under the wash-out (AUWO) (p = 0.002) and Peak Intensity (p = 0.005). Also slope of wash-in changed significantly (p = 0.003). An important reduction in Standard Uptake Values (SUV) recorded in 7/11 patients (PFS >18 months). Decrease in DCE-US AUC, AUWI and AUWO values on day 7 were predictive of PET-CT results.

CONCLUSIONS

AUC AUWI, AUWO are the DCE-US parameters related to blood volume that at D 15 can predict the response of GISTs to treatment with masatinib. Additional studies are ongoing.

DOG1 and CD117 are the antibodies of choice in the diagnosis of gastrointestinal stromal tumours

AIMS

The histopathological diagnosis of gastrointestinal stromal tumours (GIST) is typically made based on a combination of clinical and morphological features supported by immunohistochemistry studies. The aim of this study was to examine the staining quality, sensitivity, specificity and utility of antibodies used commonly in GIST diagnosis.

METHODS AND RESULTS

Immunohistochemistry with a panel of antibodies [CD117, DOG1, protein kinase C (PKC)-theta, nestin, CD34, smooth muscle actin (SMA), desmin, S100 and CD171] was performed on whole sections from 187 GIST and 29 gastrointestinal mesenchymal tumours, and on several microarrays including 355 GISTs and 120 soft tissue sarcomas. Results showed that DOG1 and CD117 were the most sensitive and specific antibodies used in GIST diagnosis. PKC-theta and nestin were sensitive, but less specific, also staining other spindle cell tumours commonly considered in the differential diagnosis of GIST. CD34 staining was less sensitive than many of the other antibodies and of limited aid in diagnosis. The smooth muscle markers SMA and desmin, together with the neural marker S100, were unhelpful in confirming a diagnosis of GIST, but were particularly useful in the exclusion/diagnosis of other gastrointestinal mesenchymal tumour types.

CONCLUSIONS

In the majority of histologically suspected GISTs a combination of CD117 and DOG1 immunostaining is sufficient to confirm the histological diagnosis.

Adjuvant and neoadjuvant therapy for primary GIST

Adjuvant therapy for primary GIST has proven benefit in extending disease free survival. Defined risk factors for recurrent disease are based on GIST size, location, and mitotic rate and provide useful guidelines for selecting patients for adjuvant therapy considerations. Neoadjuvant therapy with tyrosine kinase inhibition has potential usefulness in primary GIST, although not yet as standard of care. Advantages can include tumor downsizing to provide opportunity for less morbid surgical resection as well as to decrease risk of intra-op tumor rupture. These theoretical considerations have not been evaluated in large clinical studies.

Giant ileal gastrointestinal stromal tumour presenting as an intestinal subocclusion and subsequent haemoperitoneum: a case report and a review of the literature

We describe a case of a 76-year-old man with a giant ileal gastrointestinal stromal tumour (GIST) causing an intestinal subocclusion and a subsequent haemoperitoneum. During his hospital stay for a sudden hypovolemic shock, the patient underwent an urgent laparotomy and a 20 cm × 15 cm ruptured ileal GIST causing haemoperitoneum was found. Only 13 cases of ileal GIST causing peritoneal bleeding have been described since 2000, the one we presented is the largest. Although rare this pathological entity should be kept in mind in case of sudden abdominal pain and hypovolemic shock in patients with a large intraabdominal mass.

Gastrointestinal Stromal Tumors: Actin Expression, a New Prognostic Factor?

The aim of this study is to analyze the clinical outcome of gastrointestinal stromal tumors (GISTs) and to determine new prognostic factors. We perform a retrospective study of all the patients diagnosed with GIST in any location and operated on between 2000 and 2008 at our institution. We analyzed 35 patients, 16 males (45.7%) and 19 females (54.3%), with a mean age of 64 ± 13.8 years. The tumors were located in the stomach in 22 patients (62.9%), in the small bowel in 10 (28.6%), and the retroperitoneum in three (8.6%). Referring to gastric GIST, endoscopy revealed an ulceration in the mucosa in five cases, suggesting an epithelial neoplasm. In all these cases, pathology of the biopsy specimen was nonconclusive. Survival rate at 1 and 5 years was 94.3 and 88.6 per cent, respectively. Disease-free survival at 1 and 2 years was 91.4 and 88.6 per cent, respectively. Analyzing prognostic factors, a lower disease-free survival was observed among patients with constitutional syndrome at diagnosis ( P = 0.000), small bowel GIST ( P = 0.037), and tumors not expressing actin ( P = 0.015). A lower global survival was observed among men ( P = 0,036), patients with an abdominal mass ( P = 0.033) or with constitutional syndrome ( P = 0.007) at diagnosis and tumors at a retroperitoneal location ( P = 0.0002). Gastric GIST may be confused with epithelial neoplasms, modifying the surgery. In our patients, masculine gender, constitutional syndrome and abdominal mass at diagnosis, small bowel and retroperitoneal location, and actin negative tumors are bad prognostic factors.

Clinicopathological and immunohistochemical features of gastointestinal stromal tumors

PURPOSE

The purpose of this study was to evaluate the clinicopathological features and immunohistochemical features of gastrointestinal stromal tumor (GIST), and specifically the expressions of platelet derived growth factor receptor A (PDGFRA), protein kinase C theta (PKC theta), discovered on GIST-1 (DOG-1), p16 and p27.

MATERIALS AND METHODS

Total 118 patients who underwent surgical resection for GIST at our institution between Jan 1997 and Dec 2007 were retrospectively studied. Immunohistochemical staining for c-kit, PDGFRA, PKC-theta, DOG-1, p16 and p27 was performed on a tissue microarray of the 118 GIST. The clinicopathologic parameters, the disease-free survival (DFS) and the overall survival rate were analyzed along with immunohistochemistry.

RESULTS

The immunohistochemical stains for c-kit, CD34, PKC-theta, PDGFRA, DOG-1, p16 and p27 were positive in 89.8%, 72.0%, 56.8%, 94.9%, 90.7%, 69.5% and 44.1% of the tumor samples, respectively. The immunohistochemical expression of c-kit was strongly correlated with PKC-theta (p=0.000), DOG-1 (p=0.000) and CD34 (p=0.002). The DFS rate was significantly decreased for the patients with peritoneal GIST, high risk GIST, ≥10 cm-sized GIST, ≥10 mitoses/50 high power fields (HPFs) and p16 positivity (p=0.001, p=0.004, p=0.001, p=0.003 and p=0.028). GISTs ≥10 cm, epithelioid tumor cell type, and c-kit, and DOG-1 negativity were significantly associated with shorter period of overall survival (p=0.048, p=0.006, p=0.000 and p=0.000).

CONCLUSION

The expression of p16 and no expression of c-kit and DOG-1 in GISTs, as well as peritoneal tumor site, high risk group, large tumor size, epithelioid tumor cell type and numerous mitoses, may be potentially prognostic factors for predicting worse outcome for patients who suffer from GIST.

Diagnosis, treatment and prognosis of gastrointestinal stromal tumors: an analysis of 67 cases

AIM: To investigate the clinical characteristics of and prognostic factors for gastrointestinal stromal tumors (GIST).

METHODS: The clinicopathological data for 67 patients with gastrointestinal tumors treated between January 2002 and October 2008 at our hospital were analyzed retrospectively. All these patients were treated by surgery. Kaplan-Meier survival analysis and Cox regression model were used to evaluate the prognostic factors for GIST.

RESULTS: Of all the 67 cases, 31 tumors were located in the stomach, 23 in the small intestine, 7 in the rectum, and 6 were out of the gastrointestinal tract. The positive rates of CD117 and CD34 expression were 97.0% and 85.1%, respectively. The 1-, 3- and 5-year survival rates in 53 patients undergoing follow-up were 96.2%, 81.1% and 70.5%, respectively. Univariate analysis revealed that the risk classification of GIST published by National Institute of Health (NIH) in 2008 was associated with the survival rate in GIST patients. In the high-risk group, adjuvant imatinib mesylate therapy after surgery improved the prognosis significantly. Multivariate analysis using Cox hazard proportional model revealed that the risk classification and administration of imatinib mesylate could affect the prognosis of GIST patients.

CONCLUSION: The NIH risk classification for GIST and imatnib mesylate treatment are related to the survival rate of GIST patients. Surgical resection is still the main therapy for GIST though targeted therapy will play a more important role in future. As postoperative recurrence mainly occurs in the high-risk group, these GIST patients will get more benefit from adjuvant Gleevec treatment.

Multiple gastrointestinal stromal tumors in a patient with type I neurofibromatosis presenting with tumor rupture and peritonitis

A young woman with type 1 neurofibromatosis (NF-1) complained of abdominal pain for 3 days. Computed tomography disclosed two jejunal tumors with rupture and peritonitis. Surgery revealed two tumors in the jejunum, one of which was ruptured. Specimen examination found four additional intramural nodules between these tumors. Histology proved these tumors were all gastrointestinal stromal tumors (GIST). The finding of multiple digestive tumors associated with peritonitis in an NF-1 patient should lead to the consideration of a ruptured GIST.

Significance of expression of metastasis-related factors uPA, MMP-2, MMP-9 and TGF-β1 in gastrointestinal stromal tumors

AIM: To investigate the significance of expression of urokinase-type plasminogen activator (uPA), matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9) and transforming growth factor-β1 (TGF-β1) in gastrointestinal stromal tumors (GISTs).

METHODS: The expression of uPA, MMP-2, MMP-9 and TGF-β1 mRNAs and proteins in 124 GISTs specimens was detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot, respectively.

RESULTS: In gastrointestinal stromal tumors, the mRNA expression of uPA, MMP-2, MMP-9 and TGF-β1 is closely correlated with tumor stage (NIH classification), mucosal invasion and lymphatic metastasis. The mRNA expression levels of uPA, MMP-2, MMP-9 and TGF-β1 were up-regulated with increasing tumor stage, showing significant differences among low-, moderate- and high-risk GISTs. The positive rates of uPA, MMP-2, MMP-9 and TGF-β1 mRNA expression was not correlated with age, sex and histological type. Similar results were obtained for the expression of uPA, MMP-2, MMP-9 and TGF-β1 proteins in GISTs. The expression of uPA protein is positively correlated with that of TGF-β1, MMP-2 and MMP-9 (r = 0.356, 0.323 and 0.346, respectively).

CONCLUSION: The positive activation of TGF-β1 in GISTs possibly up-regulates uPA expression which in turn activates MMP-2 and MMP-9. The activation of MMP-2 and MMP-9 may lead to the degradation of extracellular matrix degradation and promote tumor invasion and metastasis.

Gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) have emerged from being poorly defined, treatment-resistant tumors to a well-recognized, well-understood, and treatable tumor entity within only one decade. The understanding of GIST biology has made this tumor a paradigm for molecularly targeted therapy in solid tumors and provides informative insights into the advantages and limitations of so-called targeted therapeutics. Approximately 85% of GISTs harbor activating mutations in KIT or the homologous receptor tyrosine kinase PDGFRA gene. These mutations are an early event in GIST development and the oncoproteins serve as a target for the small molecule tyrosine kinase inhibitors imatinib and sunitinib. The existing and emerging treatment options demand exact morphologic classification and risk assessment. Although, KIT (CD117) immunohistochemistry is a reliable diagnostic tool in the diagnosis of GIST, KIT-negative GISTs, GISTs showing unusual morphology as well as GISTs which progress during or after treatment with imatinib/sunitinib can be a challenge for pathologists and clinicians. This review focuses on GIST pathogenesis, morphologic evaluation, promising new immunohistochemical markers, risk assessment, the role of molecular analysis, and the increasing problem of secondary imatinib resistance and its mechanisms.

Clinical implications of expression of MAGE-1 and NY-ESO-1 mRNAs in gastrointestinal stromal tumors

AIM: To evaluate the possibility of using melanoma antigen-1 (MAGE-1) and New York-esophageal-1 (NY-ESO-1) antigens as specific targets for immunotherapy of gastrointestinal stromal tumors (GISTs) and using MAGE-1 and NY-ESO-1 mRNA levels as auxiliary parameters for risk classification of GISTs.

METHODS: The expression of MAGE-1 and NY-ESO-1 mRNAs was detected by reverse transcription-polymerase chain reaction (RT-PCR) in 30 GIST tissue specimens. The correlation of MAGE-1 and NY-ESO-1 mRNA expression with pathological parameters was analyzed in GISTs.

RESULTS: The positive rates of MAGE-1 and NY-ESO-1 mRNA expression in GIST specimens were 30% and 47%, respectively. At least one of these two cancer-testis antigens (CTAs) was detected in 18 GIST tissue specimens. The expression of MAGE-1 and NY-ESO-1 mRNAs was not correlated with age, sex or pathologic type (P > 0.05), but correlated with tumor site, tumor diameter and risk grade (all P < 0.05). The expression levels of MAGE-1 and NY-ESO-1 mRNAs in GISTs of high risk grade were significantly higher than those in GISTs of low risk grade (P < 0.05). No negative correlation was noted between the expression of MAGE-1 and NY-ESO-1 mRNAs in GISTs (r = 0.018, P > 0.05).

CONCLUSION: MAGE-1 and NY-ESO-1 mRNAs are expressed specifically in GIST tissue and may be potentially promising targets for antigen-specific immunotherapy of GISTs. The expression of MAGE-1 and NY-ESO-1 mRNAs is correlated with the risk grade of GISTs. MAGE-1 and NY-ESO-1 mRNA levels are promising auxiliary parameters for risk classification of GISTs.

Diagnosis and treatment of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract with malignant potential. Because of the lack of specific clinical manifestations, an accurate preoperative diagnosis of GIST is very difficult. In recent years, the pathogenesis of GIST has been gradually clarified, and their diagnosis and treatment have been greatly improved. Oncogenic mutation of the KIT receptor tyrosine kinase is found in the majority of patients with GIST. Immunohistochemical detection of markers such as CD117 is key to the diagnosis of GIST. Although combined therapy has been emphasized recently, radical surgical treatment is still the most effective option for GIST. Postoperative molecular targeted therapies, including neoadjuvant therapy and adjuvant therapy, can greatly improve the outcomes of patients with GIST. The development of imatinib offers new hope to patients with GIST.

High density DNA array analysis reveals distinct genomic profiles in a subset of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) generally harbor activating mutations in KIT or platelet-derived growth facter receptor (PDGFRA). Mutations in these receptor tyrosine kinases lead to dysregulation of downstream signaling pathways that contribute to GIST pathogenesis. GISTs with KIT or PDGFRA mutations also undergo secondary cytogenetic alterations that may indicate the involvement of additional genes important in tumor progression. Approximately 10-15% of adult and 85% of pediatric GISTs do not have mutations in KIT or in PDGFRA. Most mutant adult GISTs display large-scale genomic alterations, but little is known about the mutation-negative tumors. Using genome-wide DNA arrays, we investigated genomic imbalances in a set of 31 GISTs, including 10 KIT/PDGFRA mutation-negative tumors from nine adults and one pediatric case and 21 mutant tumors. Although all 21 mutant GISTs exhibited multiple copy number aberrations, notably losses, eight of the 10 KIT/PDGFRA mutation-negative GISTs exhibited few or no genomic alterations. One KIT/PDGFRA mutation-negative tumor exhibiting numerous genomic changes was found to harbor an alternate activating mutation, in the serine-threonine kinase BRAF. The only other mutation-negative GIST with significant chromosomal imbalances was a recurrent metastatic tumor found to harbor a homozygous deletion in chromosome arm 9p. Similar findings in several KIT-mutant GISTs identified a minimal overlapping region of deletion of approximately 0.28 Mbp in 9p21.3 that includes only the CDKN2A/2B genes, which encode inhibitors of cell-cycle kinases. These results suggest that GISTs without activating kinase mutations, whether pediatric or adult, generally exhibit a much lower level of cytogenetic progression than that observed in mutant GISTs.

Insulin-like growth factor binding protein-3 has dual effects on gastrointestinal stromal tumor cell viability and sensitivity to the anti-tumor effects of imatinib mesylate in vitro

Background

Imatinib mesylate has significantly improved survival and quality of life of patients with gastrointestinal stromal tumors (GISTs). However, the molecular mechanism through which imatinib exerts its anti-tumor effects is not clear. Previously, we found up-regulation of insulin-like growth factor binding protein-3 (IGFBP3) expression in imatinib-responsive GIST cells and tumor samples. Because IGFBP3 regulates cell proliferation and survival and mediates the anti-tumor effects of a number of anti-cancer agents through both IGF-dependent and IGF-independent mechanisms, we hypothesized that IGFBP3 mediates GIST cell response to imatinib. To test this hypothesis, we manipulated IGFBP3 levels in two imatinib-responsive GIST cell lines and observed cell viability after drug treatment.

Results

In the GIST882 cell line, imatinib treatment induced endogenous IGFBP3 expression, and IGFBP3 down-modulation by neutralization or RNA interference resulted in partial resistance to imatinib. In contrast, IGFBP3 overexpression in GIST-T1, which had no detectable endogenous IGFBP3 expression after imatinib, had no effect on imatinib-induced loss of viability. Furthermore, both the loss of IGFBP3 in GIST882 cells and the overexpression of IGFBP3 in GIST-T1 cells was cytotoxic, demonstrating that IGFBP3 has opposing effects on GIST cell viability.

Conclusion

This data demonstrates that IGFBP3 has dual, opposing roles in modulating GIST cell viability and response to imatinib in vitro. These preliminary findings suggest that there may be some clinical benefits to IGFBP3 therapy in GIST patients, but further studies are needed to better characterize the functions of IGFBP3 in GIST.

Surgery for gastrointestinal stromal tumors of the duodenum

BACKGROUND

Duodenal gastrointestinal stromal tumors (GISTs) represent a unique dilemma with varied surgical treatment options. However, the impact of operative methods on disease recurrence has never been addressed.

METHODS

We retrospectively reviewed the medical records of all patients with duodenal GISTs treated at our hospital from January 2001 to December 2008.

RESULTS

Of the 25 patients included for analysis, 9 had pancreaticoduodenectomy (PD) and 16 had limited operation. Comparison of clinicopathological data between tumors treated by PD and by limited operation showed no significant differences in patient age, sex, symptoms, location of tumor, tumor grade, immunohistochemical staining pattern, or complications after surgery. However, patients with tumors >5 cm (P = 0.005) or not diagnosed as GISTs before surgery (P = 0.004) were significantly more frequently treated by PD. In multivariable analysis, the only significant predictor for disease recurrence was high-risk duodenal GISTs.

CONCLUSIONS

Based on the fact that type of operation was not correlated to operative risk and disease recurrence, limited operation rather than PD should be attempted for duodenal GIST without involvement of papilla of Vater to preserve more pancreas parenchyma, duodenum, and common bile duct.

Low frequency of MAP kinase pathway alterations in KIT and PDGFRA wild-type GISTs

AIMS

Gastrointestinal stromal tumours (GISTs) are commonly driven by oncogenic mutations in KIT and PDGFRA. However, 10-40% of these patients are wild-type for these genes. The prognostic significance of wild-type GISTs is controversial, and they rarely respond to imatinib. The aim of this study was to elucidate the molecular lesions underlying wild-type GISTs tumorigenesis.

METHODS AND RESULTS

Twenty-nine KIT and PDGFRA wild-type GISTs were re-assessed for the presence of 'cryptic'KIT exon 11 duplications. Using a specific polymerase chain reaction assay, three previously undetected mutations were identified. In the remaining 26 wild-type GISTs, KIT, stem cell factor (SCF), phospho-KIT and phospho-ERK expression was evaluated by immunohistochemistry. Samples were screened for gain-of-function mutations in the mitogen-activated protein kinase (MAPK) cascade. KIT and SCF co-expression associated with KIT activation was observed in approximately 30% of cases. Furthermore, phospho-ERK expression showed that MAPK is activated in approximately 30% of cases. None of RAS family (H-, K- and N-RAS) oncogenes exhibited activating mutations, whereas BRAF mutations were found in approximately 4% of cases.

CONCLUSIONS

In the absence of RAS mutations, MAPK could be activated through SCF/KIT autocrine/paracrine mechanisms and/or mutated BRAF in a subset of KIT/PDGFRA wild-type GISTs.