Gastrointestinal stromal tumors: disease and treatment update

Factors associated with gastrointestinal stromal tumor rupture and pathological risk: A single-center retrospective study

BACKGROUND

Gastrointestinal stromal tumor (GIST) is a rare gastrointestinal mesenchymal tumor with potential malignancy. Once the tumor ruptures, regardless of tumor size and mitotic number, it can be identified into a high-risk group. It is of great significance for the diagnosis, treatment, and prognosis of GIST if non-invasive examination can be performed before surgery to accurately assess the risk of tumor.

AIM

To identify the factors associated with GIST rupture and pathological risk.

METHODS

A cohort of 50 patients with GISTs, as confirmed by postoperative pathology, was selected from our hospital. Clinicopathological and computed tomography data of the patients were collected. Logistic regression analysis was used to evaluate factors associated with GIST rupture and pathological risk grade.

RESULTS

Pathological risk grade, tumor diameter, tumor morphology, internal necrosis, gas-liquid interface, and Ki-67 index exhibited significant associations with GIST rupture (P < 0.05). Gender, tumor diameter, tumor rupture, and Ki-67 index were found to be correlated with pathological risk grade of GIST (P < 0.05). Multifactorial logistic regression analysis revealed that male gender and tumor diameter ≥ 10 cm were independent predictors of a high pathological risk grade of GIST [odds ratio (OR) = 11.12, 95% confidence interval (95%CI): 1.81-68.52, P = 0.01; OR = 22.96, 95%CI: 2.19-240.93, P = 0.01]. Tumor diameter ≥ 10 cm, irregular shape, internal necrosis, gas-liquid interface, and Ki-67 index ≥ 10 were identified as independent predictors of a high risk of GIST rupture (OR = 9.67, 95%CI: 2.15-43.56, P = 0.01; OR = 35.44, 95%CI: 4.01-313.38, P < 0.01; OR = 18.75, 95%CI: 3.40-103.34, P < 0.01; OR = 27.00, 95%CI: 3.10-235.02, P < 0.01; OR = 4.43, 95%CI: 1.10-17.92, P = 0.04).

CONCLUSION

Tumor diameter, tumor morphology, internal necrosis, gas-liquid, and Ki-67 index are associated with GIST rupture, while gender and tumor diameter are linked to the pathological risk of GIST. These findings contribute to our understanding of GIST and may inform non-invasive examination strategies and risk assessment for this condition.

Emerging Targeted Therapeutic Strategies to Overcome Imatinib Resistance of Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GISTs) are the most common malignant mesenchymal neoplasms of the gastrointestinal tract. The gold standard for the diagnosis of GISTs is morphologic analysis with an immunohistochemical evaluation plus genomic profiling to assess the mutational status of lesions. The majority of GISTs are driven by gain-of-function mutations in the proto-oncogene c-KIT encoding the tyrosine kinase receptor (TKR) known as KIT and in the platelet-derived growth factor-alpha receptor (PDGFRA) genes. Approved therapeutics are orally available as tyrosine kinase inhibitors (TKIs) targeting KIT and/or PDGFRA oncogenic activation. Among these, imatinib has changed the management of patients with unresectable or metastatic GISTs, improving their survival time and delaying disease progression. Nevertheless, the majority of patients with GISTs experience disease progression after 2-3 years of imatinib therapy due to the development of secondary KIT mutations. Today, based on the identification of new driving oncogenic mutations, targeted therapy and precision medicine are regarded as the new frontiers for GISTs. This article reviews the most important mutations in GISTs and highlights their importance in the current understanding and treatment options of GISTs, with an emphasis on the most recent clinical trials.

Cardiovascular-Specific Mortality among Gastrointestinal Stromal Tumor Patients: A Population-Based Analysis

Background

The overall risk of cardiovascular mortality (CVM) in cancer survivors has increased with time. The trend of CVM in patients with gastrointestinal stromal tumors (GISTs) remains unclear. This study is aimed at assessing the risks and independent predictors of CVM in GIST patients.

Methods

Data of the GIST patients were extracted from the Surveillance, Epidemiology, and End Results (SEER) database (2000-2019). The standardized mortality ratio (SMR) was used to evaluate the risk of CVM, and a multivariate competing risk model was utilized to identify the predictors for CVM.

Results

A total of 12,058 patients with GIST were included in this study, of whom 477 (4.0%) patients died of cardiovascular disease (CVD). The SMR for CVM among GIST patients was significantly higher than in the general population (SMR, 3.23, 95% CI: 2.97-3.52), and all categories of CVD were associated with a significantly elevated SMR. The cumulative mortality of CVD was the lowest among all causes of death, while the CVM was the second most common cause of death in patients ≥ 80 years when stratified by age at diagnosis. Furthermore, male sex, older age at diagnosis, White race, unmarried, earlier year of diagnosis, and not receiving chemotherapy were the poor prognostic factors for CVM.

Conclusions

The CVM risk in GIST patients was significantly higher relative to the general US population. Timely screening and cardioprotective interventions should be implemented to prevent the occurrence of CVM in patients with GIST.

Association Between the Nutritional Risk and the Survival Rate in Newly Diagnosed GIST Patients

Background: Currently, the incidence of gastrointestinal stromal tumors (GIST) is increasing rapidly worldwide. Malnutrition may increase the risk of perioperative complications and affect the prognosis of patients. However, previous studies on the nutritional status of GIST patients and its impact on prognosis are limited. Therefore, this study aims to explore the incidence of malnutrition in newly diagnosed GIST patients, the proportion of participants in need of nutritional intervention, and the relationship between nutritional status and overall survival (OS). Methods: We retrospectively analyzed the clinical data of GIST patients treated in our hospital from January 2014 to January 2018. Nutritional Risk Screening 2002 (NRS2002) and Patient-Generated Subjective Global Assessment (PG-SGA) were used to assess the nutritional status of all patients. This study was to investigate the clinical significance of PG-SGA by analyzing the relationship between PG-SGA score and OS. Results: A total of 1,268 newly diagnosed GIST patients were included in this study, of which 77.76% were at risk of malnutrition (NRS2002 score ≥ 3), and the incidence of malnutrition was 10.09% (PG-SGA score ≥ 4). Meanwhile, we found 2.29% of the patients required urgent nutritional support (PG-SGA score ≥ 9). Multivariate analysis showed that age (p = 0.013), BMI (p = 0.001), weight loss (p = 0.001), anemia (p = 0.005), pre-albumin (p = 0.010), albumin (p = 0.002), tumor location (p = 0.001), tumor size (p = 0.002), and NIH classification (p = 0.001) were risk factors for nutritional status. The prognosis was significantly in GIST patients with different PG-SGA score at admission (p < 0.05). Conclusion: This study suggested that malnutrition is common in newly diagnosed GIST patients, and the higher the PG-SGA score, the worse the clinical outcome.

Dissecting the Role of Circular RNAs in Sarcomas with Emphasis on Osteosarcomas

Circular RNAs (circRNAs) are single-stranded RNAs generated from exons back-splicing from a single pre-mRNA, forming covalently closed loop structures which lack 5'-3'-polarity or polyadenylated tail. Ongoing research depicts that circRNAs play a pivotal role in tumorigenesis, tumor progression, metastatic potential and chemoresistance by regulating transcription, microRNA (miRNA) sponging, RNA-binding protein interactions, alternative splicing and to a lesser degree, protein coding. Sarcomas are rare malignant tumors stemming from mesenchymal cells. Due to their clinically insidious onset, they often present at advanced stage and their treatment may require aggressive chemotherapeutic or surgical options. This review is mainly focused on the regulatory functions of circRNAs on osteosarcoma progression and their potential role as biomarkers, an area which has prompted lately extensive research. The attributed oncogenic role of circRNAs on other mesenchymal tumors such as Kaposi Sarcoma (KS), Rhabdomyosarcoma (RMS) or Gastrointestinal Stromal Tumors (GISTs) is also described. The involvement of circRNAs on sarcoma oncogenesis and relevant emerging diagnostic, prognostic and therapeutic applications are expected to gain more research interest in the future.

Multiple jejunal gastrointestinal stromal tumors and Neurofibromatosis type 1: A rare association

INTRODUCTION AND IMPORTANCE

The association between gastrointestinal stromal tumor (GIST), mesenchymal tumor arising from the interstitial cells of cajal and Neurofibromatosis type 1 (NF1), an autosomal dominant disease has been reported in the literature. GIST in NF1 patients are multiple and located in the small intestine. Tumorigenesis in NF1 associated GIST is different to that of sporadic GIST and hence the treatment. Here we report a rare case of an NF1 patient with multiple jejunal GISTs.

CASE PRESENTATION

We here present a rare case of a 57-year-old male diagnosed with NF1 30 years back, presented in our emergency department with complaints of black, tarry stools later diagnosed to have multiple GIST in jejunum. Contrast enhanced computed tomography (CECT) of the abdomen showed a large 10.1 × 7.33 × 6.2 cm heterogeneous, exophytic, solid mass with cystic areas originating from the jejunum. The microscopic examination of the specimen showed spindle shaped tumor cells while immunohistochemistry showed CD117 (c-KIT) and DOG-1 positivity. The primary treatment was complete surgical excision of the tumor.

CLINICAL DISCUSSION

The incidence of GISTs in NF1 patient is around 6-7%; however, concomitant presence of multiple GISTs is rare. CECT of abdomen along with histopathological and immunohistochemistry studies are diagnostic. The management of GIST includes surgical and adjuvant therapy methods based on the tumorigenesis and recurrent risk stratification.

CONCLUSION

Early clinical suspicion and imaging aids in early detection of the tumor in patients with NF1 presenting with gastrointestinal symptoms. Postoperatively, screening for recurrence with radiology is of utmost importance.

LncRNA-HOTAIR activates autophagy and promotes the imatinib resistance of gastrointestinal stromal tumor cells through a mechanism involving the miR-130a/ATG2B pathway

Gastrointestinal stromal tumors (GISTs) are common neoplasms of the gastrointestinal tract that can be treated successfully using C-kit target therapy and surgery; however, imatinib chemoresistance is a major barrier to success in therapy. The present study aimed to discover alternative pathways in imatinib-resistant GISTs. Long noncoding RNAs (lncRNAs) are newly discovered regulators of chemoresistance. Previously, we showed that the lncRNA HOTAIR was upregulated in recurrent GISTs. In this study, we analyzed differentially expressed lncRNAs after imatinib treatment and found that HOTAIR displayed the largest increase. The distribution of HOTAIR in GISTs was shifted from nucleus to cytoplasm after imatinib treatments. The expression of HOTAIR was validated as related to drug sensitivity through Cell Counting Kit-8 assays. Moreover, HOTAIR was associated strongly with cell autophagy and regulated drug sensitivity via autophagy. Mechanistically, HOTAIR correlated negatively with miRNA-130a in GISTs. The downregulation of miRNA-130a reversed HOTAIR-small interfering RNA-induced suppression of autophagy and imatinib sensitivity. We identified autophagy-related protein 2 homolog B (ATG2B) as a downstream target of miR-130a and HOTAIR. ATG2B downregulation reversed the effect of pEX-3-HOTAIR/miR-130a inhibitor on imatinib sensitivity. Finally, HOTAIR was shown to influence the autophagy and imatinib sensitivity of GIST cells in mouse tumor models. Our results suggested that HOTAIR targets the ATG2B inhibitor miR-130a to upregulate the level of cell autophagy so that promotes the imatinib resistance in GISTs.

A Diagnostic Dilemma of Bleeding Gastric Tumor or Bleeding Pancreatic Tumor

Gastrointestinal stromal tumors are the most common nonepithelial tumors of the gastrointestinal tract. The stomach is the most common site of occurrence. Most of the tumors are asymptomatic. Many patients may present with mass per abdomen, gastrointestinal bleed. Tumors arising from the stomach's posterior wall may grow large, and on imaging, it may create confusion of the site of origin. We present a case of gastrointestinal stromal tumor arising from the stomach's posterior wall, growing large and creating a confusion of site of origin.

GIST associated with von recklinghausen disease: Report of two cases and review of literature

INTRODUCTION AND IMPORTANCE

Neurofibromatosis type 1 (NF1), or Von Recklinghausen's disease, is an autosomal dominant condition that affects the central nervous system. Gastrointestinal stromal tumor (GIST) refers to non-epithelial tumors of the gastrointestinal tract lacking smooth muscle structural features and schwann cell immunohistochemical characteristics. The risk of patients with NF1 to develop a GIST is 7%.

CASE PRESENTATION

GIST is a soft tissue sarcoma that probably arises from the interstitial Cajal cells of the intestine. GIST associated with NF1 syndrome appears to have a distinct phenotype, occurring in younger patients compared to sporadic GIST.

CLINICAL DISCUSSION

The clinical presentation can be highly variable, the association of gastrointestinal tumors associated with Von Recklinghausen's disease is up to 7%, postoperative treatment with imatinib is reserved for patients with a high risk of recurrence.

CONCLUSION

The treatment of primary GIST is complete surgical resection with free microscopic margins and an intact pseudocapsule.

Pheochromocytoma and gastrointestinal stromal tumours in an adult neurofibromatosis type 1 patient: a rare co-occurrence

The risk of tumours including pheochromocytoma and gastrointestinal stromal tumour (GIST) has been reported to be higher in neurofibromatosis type 1 (NF1) patients. The concomitant occurrence of these two tumours was rare in NF1 patient and most were symptomatic. In this case report, we describe the case of a 47-year-old man with NF1 who presented with microscopic haematuria. Neither hypertension nor any gastrointestinal symptoms were reported by the patient. While investigating for haematuria, left adrenal mass and arterial enhancing lesions in the small bowel were incidentally documented during computerised urography. The patient subsequently underwent a left adrenalectomy and small bowel resection. The pheochromocytoma and multiple GIST tumours were diagnosed based on pathology. Here, we discuss the rare association of pheochromocytoma and GIST and the asymptomatic presentation of those tumours in an NF1 patient. We further suggest that in NF1 patients a heightened level of vigilance can help identify this infrequent combination.

Coexistence of Von Willebrand disease and gastrointestinal stromal tumor (G.I.S.T): Case report of a rare and challenge association

Von Willebrand disease (VWD) is the most common inherited bleeding disorder and is caused by a quantitative (type 1 and 3) or qualitative (type 2) defect of Von Willebrand factor (VWF). Bleeding from the gastrointestinal (GI) tract is not uncommon in VWD and is usually associated with angiodysplasia. We report herein on the management of a patient affected by VWD2B with severe GI bleeding secondary to gastrointestinal stromal tumor (GIST) complicated by deep vein thrombosis (DVT). The current case demonstrated that the hemostatic balance, in RBDs under specific circumstances, can range from a tendency toward a hemorrhagic to normal or prothrombotic state. In these patients, a close collaboration between hematologists and surgeons can guarantee appropriate management in high-risk clinical scenarios.

Gastrointestinal stromal tumour of stomach: Feasibility of laparoscopic resection in large lesions and its long-term outcomes

Background:

Gastric gastrointestinal stromal tumours (GISTs) are rare neoplasms that require excision for cure. Although the feasibility of laparoscopic resection of smaller gastric GIST has been established, the feasibility and long-term efficacy of these techniques are unclear in larger lesions. This study is done to assess the feasibility of the laparoscopic resection of gastric GISTs and their long-term outcomes.

Methods:

Patients who underwent laparoscopic resection of gastric GISTs were identified in a prospectively collected database. Outcome measures included patient demographics, operative findings, morbidity and histopathologic characteristics of the tumour. Patient and tumour characteristics were analysed to identify risk factors for tumour recurrence.

Results:

There were 42 patients with a mean age of 56.7 years and had a mean tumour size was 4.5 ± 2.7 cm. Laparoscopic wedge resection was the most common procedure done. There were no major perioperative complications or mortalities. All lesions had negative resection margins. At a mean follow-up of 48 months, 36/39 (92.3%) patients were disease free and 3/39 (7.6%) had progressive disease. Univariate analysis showed that there was a statistically significant association of disease progression with tumour size, high mitotic index, tumour ulceration and tumour necrosis. The presence of >10 mitotic figures/50 high-power field was an independent predictor of disease progression.

Conclusion:

Our study establishes laparoscopic resection is feasible and safe in treating gastric GISTs for tumours >5 cm size. The long-term disease-free survival in our study shows acceptable oncological results in comparison to historical open resections.

CeRNA Expression Profiling Identifies KIT-Related circRNA-miRNA-mRNA Networks in Gastrointestinal Stromal Tumour

Gastrointestinal stromal tumours (GISTs) are the most common human sarcomas and are typically located in the stomach or small intestine. Although circular RNAs (circRNAs) reportedly play vital roles in tumour oncogenesis and progression, the molecular basis of the aggressive tumour biology of these circRNAs in GISTs remains unclear. In this study, we applied SBC ceRNA microarrays to screen for tumour-specific circRNA profiles in GISTs and identified that a total of 5,770 circRNAs and 1,815 mRNAs were differentially expressed in GISTs. Three significantly differential circRNAs (circ_0069765, circ_0084097, and circ_0079471) and their host genes (KIT, PLAT, and ETV1) were also verified in 68 pairs of GISTs and adjacent normal gastrointestinal tissues by qRT-PCR. A GIST-specific circRNA-miRNA-mRNA regulatory network analysis demonstrated that the specific KIT-related regulatory networks involved the three circRNAs, the circRNA host genes and three miRNAs (miR-142-5p, miR-144-3p and miR-485-3p), which may be key regulators of GISTs that could serve as molecular biomarkers and potential therapeutic targets for this malignant disease.

Large incidental gastrointestinal stromal tumors in a patient presenting with acutely symptomatic nephrolithiasis: A case report

Gastrointestinal stromal tumors (GISTs) are rare mesenchymal neoplasms, representing approximately 1%-2% of all primary gastrointestinal malignancies. Incidental GISTs are often less than 1 cm when discovered and have been reported predominantly in obese patients undergoing surgery for other medical indications. We present the rare case of a large incidental GIST in a nonobese patient with acutely symptomatic nephrolithiasis. Large GISTs may be treated with neoadjuvant imatinib mesylate to reduce tumor size prior to surgery, though some tumors may experience little change in size despite effective treatment. Treatment response for GISTs can be monitored via imaging studies, such as computed tomography or magnetic resonance imaging, but computed tomography is generally preferred over magnetic resonance imaging.

Tumor heterogeneity in gastrointestinal stromal tumors of the small bowel: volumetric CT texture analysis as a potential biomarker for risk stratification

Background

To explore whether volumetric CT texture analysis (CTTA) can serve as a potential imaging biomarker for risk stratification of small bowel gastrointestinal stromal tumors (small bowel-GISTs).

Methods

A total of 90 patients with small bowel-GISTs were retrospectively reviewed, of these, 26 were rated as high risk, 13 as intermediate risk, and 51 as low or very low risk. Histogram parameters extracted from CT images were compared among small bowel-GISTs with different risk levels by using one-way analysis of variance. Receiver operating characteristics (ROCs) and areas under the curve (AUCs) were analyzed to determine optimal histogram parameters for stratifying tumor risk.

Results

Significant differences in mean attenuation, 10th, 25th, 50th, 75th and 90th percentile attenuation, and entropy were found among high, intermediate, and low risk small bowel-GISTs (p ≤ 0.001). Mean attenuation, 10th, 25th, 50th, 75th and 90th percentile attenuation, and entropy derived from arterial phase and venous phase images correlated significantly with risk levels (r = 0.403–0.594, r = 0.386–0.593, respectively). Entropy in venous phase reached the highest accuracy (AUC = 0.830, p < 0.001) for differentiating low risk from intermediate to high risk small bowel-GISTs, with a cut-off value of 5.98, and the corresponding sensitivity and specificity were 82.4 and 74.4%, respectively.

Conclusions

Volumetric CT texture features, especially entropy, may potentially serve as biomarkers for risk stratification of small bowel-GISTs.

Management of hemorrhage in gastrointestinal stromal tumors: a review

Gastrointestinal stromal tumors (GISTs) are relatively common mesenchymal tumors. They originate from the wall of hollow viscera and may be found in any part of the digestive tract. The prognosis of patients with stromal tumors depends on various risk factors, including size, location, presence of mitotic figures, and tumor rupture. Emergency surgery is often required for stromal tumors with hemorrhage. The current literature suggests that stromal tumor hemorrhage indicates poor prognosis. Although the optimal treatment options for hemorrhagic GISTs are based on surgical experience, there remains controversy with regard to optimum postoperative management as well as the classification of malignant potential. This article reviews the biological characteristics, diagnostic features, prognostic factors, treatment, and postoperative management of GISTs with hemorrhage.

A gastrointestinal stromal tumor with acute bleeding: Management and nursing

RATIONALE

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors involving the gastrointestinal tract. A small percentage of GISTs may cause acute gastrointestinal bleeding, which requires urgent surgical intervention.

PATIENT CONCERNS

In this case report, we present a 62-year-old male patient with who was hospitalized due to acute bleeding.

DIAGNOSES

The patient was diagnosed as GIST with low risk.

INTERVENTIONS

The patient was treated endoscopically with polidocanol sclerotherapy.

OUTCOMES

The mass was removed completely, and the patient was discharged at day 9 after operation.

LESSONS

This case indicates that GIST can present as massive upper gastrointestinal bleeding and urgent endoscopic sclerotherapy can be life-saving. The endoscopical intervention may be a good alternative for emergency.

Percutaneous microwave ablation liver partition and portal vein embolization for planned hepatectomy due to large gastrointestinal stromal tumor metastases: A case report

RATIONALE

The liver is the most frequent site of relapse of gastrointestinal stromal tumors (GISTs). Surgery is always considered to be unsuitable because of the multiple metastases.

PATIENT CONCERNS

In this report, we describe a case of large, multiple GIST liver metastases that were treated with percutaneous microwave ablation liver partition and portal vein embolization for planned hepatectomy (PALPP). A 44-year-old woman had undergone pancreaticoduodenectomy 4 years previously because of the diagnosis of a large duodenal GIST. Large, multiple liver metastases were observed 2 years later.

DIAGNOSES

GIST liver metastasis was diagnosed using percutaneous ultrasound-guided biopsy.

INTERVENTIONS

After 6 months of treatment with imatinib, the liver metastasis was stable. PALPP was performed because of insufficient future liver remnant (FLR) and right trisegmentectomy was successfully completed 10 days later.

OUTCOMES

The patient has had no signs of local or systemic disease during 17 months of postsurgical follow-up.

LESSONS

PALPP provides a new methodology for treatment of GIST liver metastasis in patients with insufficient FLR, and may have benefit in prolonging a durable remission.

Management of Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasm of the gastrointestinal tract. The stomach is the most common site of origin. Management of GISTs changed after the introduction of molecularly targeted therapies. Although the only potentially curative treatment of resectable primary GISTs is surgery, recurrence is common. Patients with primary GISTs at intermediate or high risk of recurrence should receive imatinib postoperatively. Imatinib is also first-line therapy for advanced disease. Cytoreductive surgery might be considered in advanced GIST for patients with stable/responding disease or limited focal progression on tyrosine kinase inhibitor therapy. GIST requires multidisciplinary management.

Assessing tumor vascularization as a potential biomarker of imatinib resistance in gastrointestinal stromal tumors by dynamic contrast-enhanced magnetic resonance imaging

BACKGROUND

Most metastatic gastrointestinal stromal tumors (GISTs) develop resistance to the first-line imatinib treatment. Recently, increased vessel density and angiogenic markers were reported in GISTs with a poor prognosis, suggesting that angiogenesis is implicated in GIST tumor progression and resistance. The purpose of this study was to investigate the relationship between tumor vasculature and imatinib resistance in different GIST mouse models using a noninvasive magnetic resonance imaging (MRI) functional approach.

METHODS

Immunodeficient mice (n = 8 for each cell line) were grafted with imatinib-sensitive (GIST882 and GIST-T1) and imatinib-resistant (GIST430) human cell lines. Dynamic contrast-enhanced MRI (DCE-MRI) was performed on GIST xenografts to quantify tumor vessel permeability (K ^trans) and vascular volume fraction (v _p). Microvessel density (MVD), permeability (mean dextran density, MDD), and angiogenic markers were evaluated by immunofluorescence and western blot assays.

RESULTS

Dynamic contrast-enhanced magnetic resonance imaging showed significantly increased vessel density (P < 0.0001) and permeability (P = 0.0002) in imatinib-resistant tumors compared to imatinib-sensitive ones. Strong positive correlations were observed between MRI estimates, K ^trans and v _p, and their related ex vivo values, MVD (r = 0.78 for K ^trans and r = 0.82 for v _p) and MDD (r = 0.77 for K ^trans and r = 0.94 for v _p). In addition, higher expression of vascular endothelial growth factor receptors (VEGFR2 and VEFGR3) was seen in GIST430.

CONCLUSIONS

Dynamic contrast-enhanced magnetic resonance imaging highlighted marked differences in tumor vasculature and microenvironment properties between imatinib-resistant and imatinib-sensitive GISTs, as also confirmed by ex vivo assays. These results provide new insights into the role that DCE-MRI could play in GIST characterization and response to GIST treatment. Validation studies are needed to confirm these findings.

Primary gastrointestinal stromal tumor of the liver in an anorectal melanoma survivor: A case report

The majority of gastrointestinal stromal tumors (GISTs) arise in the stomach and small intestine; primary GIST of the liver is extremely rare. GISTs share specific immunohistological features with melanoma, therefore, determining a definitive diagnosis can be difficult. However, electron microscopy can be used to aid the differential diagnosis of GIST. The present study reports the first case of a KIT/platelet-derived growth factor receptor α (PDGFRA) wild-type, primary GIST arising from the liver in a long-term survivor of anorectal melanoma. The patient underwent APR for treatment of malignant melanoma of the anorectum in 2001 with no adjuvant therapy and remained disease-free until 2009. In 2009, the patient presented with a solitary, rapidly growing hypervascular liver tumor, which was subsequently diagnosed as a primary GIST of the liver. Imatinib treatment (400 mg/day) was initially administered for two months, however, disease progression occurred. Therefore, the patient underwent chemotherapy with doxorubicin (50 mg/m²) and cisplatin (50 mg/m²) every three weeks. Although this temporarily resulted in stable disease, progression occurred five months later. Finally, oral sunitinib (37.5 mg/day) was administered; however, the patient succumbed to the disease one month later. Despite the current GIST patient exhibiting a poor response to imatinib, the present study highlights the importance of considering a second primary malignancy and performing immunohistochemical analysis upon the occurrence of a newly developed lesions in long-term remission cancer survivors.

KIT gene mutation analysis in solid tumours: biology, clincial applications and trends in diagnostic reporting

Gain-of-function mutations involving c-kit protein, a cell-surface transmembrane receptor for stem cell factor, have been identified as a key oncogenic driver in a variety of solid tumours. Coupled with the development of tyrosine kinase inhibitors such as imatinib, c-kit has emerged as a viable drug target in what seems to be a validated therapeutic concept. This review will focus on gastrointestinal stromal tumours and melanomas, two types of solid tumours most closely associated with KIT gene mutations. The biology of KIT mutations in both conditions, as well as the value of KIT mutation testing in predicting disease and treatment outcomes are discussed. Since initial response to imatinib is largely influenced by mutation status, genotyping these tumours serves to facilitate personalised oncology. We also summarise our experience with diagnostic reporting of KIT mutation analysis over a period of 3 years, and briefly survey future developments in treatment, which indeed look very promising.

[Gastroduodenal intussusception due to pedunculated polypoid gastrointestinal stromal tumor]

The gastrointestinal stromal tumor (GIST) is a mesenchymal tumor of the digestive tract showing differentiation along the line of interstitial cell of Cajal. The most GISTs in the stomach generally show the appearance of submucosal tumors. It is rare for GISTs to appear as a pedunculated polypoid lesion on endoscopy. We experienced a case of a 51-year-old man who had a pedunculated polypoid GIST. He was admitted to our hospital for nausea, vomiting, melena and severe anemia (hemoglobin 3.4 g/dL, hematocrit 10.8%). An upper endoscopy showed gastroduodenal intussusception due to a pedunculated polypoid mass. This report presents a rare case of endoscopically proven gastroduodenal intussusceptions due to pedunculated polypoid GIST in the stomach.

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.