A gist of gastrointestinal stromal tumors: A review

Understanding Gastric GIST: From Pathophysiology to Personalized Treatment

Background: Gastric gastrointestinal stromal tumors (GISTs) represent a subset of gastrointestinal tumors predominantly found in the stomach. Despite their rarity, these tumors carry significant implications for patient health and management. GISTs are potentially malignant tumors with unpredictable progression. They originate from the interstitial cells of Cajal, which are positioned between the intramural neurons and the smooth muscle cells of the digestive tract. These tumors are characterized primarily by mutations in the c-Kit gene, as well as other mutations such as those in the platelet-derived growth factor receptor alpha (PDGFRA) gene. Methods: Our comprehensive search across five databases initially yielded 2976 articles. After eliminating 197 duplicates, we screened the titles and abstracts of 2779 articles, excluding 2692 for not meeting the inclusion criteria. During the full-text screening, 16 more articles were excluded. Ultimately, 71 papers met the inclusion criteria and were included in our analysis. Results: Due to differences in study designs, inclusion criteria for patients, and reported outcomes, a meta-analysis was not conducted. The accurate diagnosis of GIST is established through histopathological examination and immunohistochemistry. Histopathologically, GISTs are classified into three main types: spindle cell, epithelioid, and mixed. The therapeutic management of GIST involves surgery, endoscopic treatment, and chemotherapy. Conclusions: The prognosis for GIST patients depends on various factors, including risk category, disease stage, applied treatments, and recurrence post-treatment. A significant recent advancement comes from artificial intelligence, which can be increasingly involved in both the diagnosis and treatment of this tumor.

A Gastrointestinal Stromal Tumor (GIST) and a Pseudocyst of the Pancreas: A Peculiar Case of Both Co-existing in the Same Patient

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal (GI) tract, typically originating from the interstitial cells of Cajal. The clinical presentations are variable according to their size and shape but rarely present as a palpable abdominal mass. Pancreatic pseudocysts are common complications of chronic pancreatitis characterized by fluid collections surrounded by a non-epithelialized wall of fibrous and granulation tissue. Patients may present with non-specific symptoms like abdominal pain, nausea, and vomiting and they generally have a history of acute pancreatitis. Small pseudocysts often resolve spontaneously, but larger ones often become symptomatic and may lead to complications. It is rare to find both a GIST of the stomach and a pseudocyst of the pancreas in the same patient. We present a unique case of a giant GIST and a pancreatic pseudocyst in a 72-year-old male who was experiencing abdominal pain and distension. Imaging revealed a massive lesion originating from the posterior gastric wall, which resembled a pseudocyst, along with a distinct cystic lesion adjacent to the pancreatic body. During surgical exploration, a complex interplay of both pathologies was discovered, requiring a comprehensive resection approach. The successful outcome highlights the importance of careful evaluation and personalized management in such rare cases.

A Rare Case of Colonic Gastrointestinal Stromal Tumor

Gastrointestinal stromal tumors (GISTs) are a type of mesenchymal tumor of the gastrointestinal tract that originate anywhere in the gastrointestinal tract, with the colon and appendix being the least recorded sites of occurrence. The following case report is that of a colonic GIST in a 53-year-old male and its histologic type. Included are notes on the recent additions and updates in the risk stratification of GISTs occurring in unusual sites with the relevant immunohistochemistry.

What may an adrenal mass conceal? Adrenal gastrointestinal stromal tumor: a case report

Extraintestinal gastrointestinal stromal tumors (GISTs) are extremely rare, and adrenal GISTs are even exceptional. Only three cases have been reported in the literature thus far, the current case being the fourth. This case demonstrates the need of including extraintestinal GIST in the differential diagnosis when investigating adrenal tumors. Herein, we present a case of adrenal GIST diagnosed in a 60-year-old female patient who had a left adrenal GIST surgically removed as an adrenal tumor.

Exploring Perforated Jejunal GIST: A Rare Case Report and Review of Molecular and Clinical Literature

This case report details a rare instance of a perforated jejunal gastrointestinal stromal tumor (GIST) in a 76-year-old female patient. The patient presented with acute abdominal pain and distension without any changes in bowel habits or episodes of nausea and vomiting. Initial diagnostics, including abdominal plain radiography and ultrasonography, were inconclusive; however, a computed tomography (CT) scan revealed pneumoperitoneum and an irregular fluid collection suggestive of small intestine perforations. Surgical intervention uncovered a 35 mm jejunal GIST with a 10 mm perforation. Histopathological examination confirmed a mixed cell type GIST with high malignancy potential, further substantiated by immunohistochemistry markers CD117, DOG1, and vimentin. Molecular analysis illuminated the role of key oncogenes, primarily KIT and PDGFRA mutations, emphasizing the importance of molecular diagnostics in GIST management. Despite the severity of the presentation, the patient's postoperative recovery was favorable, highlighting the effectiveness of prompt surgical and multidisciplinary approaches in managing complex GIST cases.

A Unique Case of Mesenteric Gastrointestinal Stromal Tumor Presenting as an Acute Abdomen

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the digestive tract and arise from the interstitial cells of Cajal in the mesenteric plexus. These tumors can originate in any part of the GI tract; however, a higher burden has been observed in the stomach and small intestines. Mesenteric GISTs are exceedingly rare, with unique clinicopathological features and a poorer prognosis. Herein, we describe a unique case of a 66-year-old female with a remote history of appendectomy who presented to the emergency room complaining of severe abdominal pain and vomiting. On imaging, the patient was found to have a large inflammatory mass associated with small bowel loops, and the pathology confirmed a mesenteric GIST. The tumor was resected, and the genomic test results confirmed the KIT (exon 11) mutation. Although the tumor had a low mitotic rate, the tumor was large enough to warrant the initiation of adjuvant imatinib mesylate for 36 months with regular bloodwork and imaging.

Esterase-Responsive Polyglycerol-Based Nanogels for Intracellular Drug Delivery in Rare Gastrointestinal Stromal Tumors

Rare gastrointestinal stromal tumors (GISTs) are caused by mutations in the KIT and PDGFRA genes. Avapritinib (BLU-285) is a targeted selective inhibitor for mutated KIT and PDGFRA receptors that can be used to treat these tumors. However, there are subtypes of GISTs that exhibit resistance against BLU-285 and thus require other treatment strategies. This can be addressed by employing a drug delivery system that transports a combination of drugs with distinct cell targets. In this work, we present the synthesis of esterase-responsive polyglycerol-based nanogels (NGs) to overcome drug resistance in rare GISTs. Using inverse nanoprecipitation mediated with inverse electron-demand Diels-Alder cyclizations (iEDDA) between dPG-methyl tetrazine and dPG-norbornene, multi-drug-loaded NGs were formed based on a surfactant-free encapsulation protocol. The obtained NGs displayed great stability in the presence of fetal bovine serum (FBS) and did not trigger hemolysis in red blood cells over a period of 24 h. Exposing the NGs to Candida Antarctica Lipase B (CALB) led to the degradation of the NG network, indicating the capability of targeted drug release. The bioactivity of the loaded NGs was tested in vitro on various cell lines of the GIST-T1 family, which exhibit different drug resistances. Cell internalization with comparable uptake kinetics of the NGs could be confirmed by confocal laser scanning microscopy (CLSM) and flow cytometry for all cell lines. Cell viability and live cell imaging studies revealed that the loaded NGs are capable of intracellular drug release by showing similar IC50 values to those of the free drugs. Furthermore, multi-drug-loaded NGs were capable of overcoming BLU-285 resistance in T1-α-D842V + G680R cells, demonstrating the utility of this carrier system.

A gist on an obscure neoplasm in Ghana: gastrointestinal stromal tumours

BACKGROUND

Gastrointestinal Stromal Tumour is a rare but potentially curable tumour of the gastrointestinal tract accounting for up to 1% of all gastrointestinal tumours. The discovery of Imatinib mesylate, a novel tyrosine kinase inhibitor has improved the chances even for unresectable, recurrent, or metastatic diseases.

METHODS

This study sought to document the clinical and pathological characteristics of GISTs from two tertiary hospitals in Ghana that have undergone immunohistochemistry confirmation between 2014 and 2021.

RESULTS

The median age of the subjects was 50 years with most of them (28.0%) being above 61 years. There were more females than males (64.0% vs. 36.0%). Abdominal mass and abdominal pain made up the majority of the clinical presentations. The majority of the subjects had partial gastrectomy (32.0%) which was followed by wedge resection (28.0%). Appendectomy and sleeve gastrectomy were the least performed procedures (8% each). Four of the 25 patients (16.0%) had resections of involved contiguous organs done with splenectomy being the most common procedure. The majority of GISTs were found in the stomach (68.0%) followed by the appendix (12.0%) and small bowel (12.0%). Gastrointestinal bleeding (55.8%) and abdominal pain (38.5%) were the most reported symptoms. Free resection margins were observed in 84.0% of the subjects and only 3/25 (12.0%) experienced tumour recurrence.

CONCLUSION

GIST is a potentially curable tumour that once was obscure but currently gaining popularity. Surgical resection offers the hope of a cure for localized disease while targeted therapies is a viable option for recurrent, metastatic, or unresectable tumours.

Imatinib plasma levels in patients with gastrointestinal stromal tumour under routine clinical practice conditions

OBJECTIVES

Imatinib is the first therapeutic option for the treatment of unresectable or metastatic gastrointestinal stromal tumours. Previous studies have shown an improvement in patient survival rates following the use of imatinib. Nevertheless, adequate plasma concentrations of imatinib are necessary to achieve such improvement in survival and limit the toxicity of the drug. This study aims to analyse the influence of imatinib plasma concentrations on efficacy and safety in the treatment of gastrointestinal stromal tumour.

MATERIALS AND METHODS

This descriptive, multicentre study analysed plasma levels of imatinib in patients diagnosed with gastrointestinal stromal tumour in the period 2019-2020. An optimal therapeutic range of 750-1500 ng/mL was established for the patient stratification based on their minimum plasma concentrations measured at the steady state.

RESULTS

This study included 11 patients with metastatic disease in total, among whom only 54.5% (n  =  6) had a minimum plasma concentrations measured at the steady state value within the therapeutic range. A median progression-free survival of 7.0 months was recorded for those patients with minimum plasma concentrations measured at the steady state < 750 ng/mL, while that median progression-free survival value remained unachieved for the group with minimum plasma concentrations measured at the steady state > 750 ng/mL (p  =  0.005). The toxicity rate was 25% and 14.3% for patients with minimum plasma concentrations measured at the steady state > 1500 ng/mL and minimum plasma concentrations measured at the steady state ≤1500 ng/mL, respectively (p  =  0.66).

CONCLUSIONS

The present study aims to describe the correlation between the toxicity and effectiveness of imatinib as a function of minimum plasma concentrations measured at the steady state under routine clinical practice conditions. The results described here show the usefulness of imatinib plasma concentrations monitoring as part of the standard daily routine in our hospitals.

Imaging of Gastrointestinal Tract Ailments

Gastrointestinal (GI) disorders comprise a diverse range of conditions that can significantly reduce the quality of life and can even be life-threatening in serious cases. The development of accurate and rapid detection approaches is of essential importance for early diagnosis and timely management of GI diseases. This review mainly focuses on the imaging of several representative gastrointestinal ailments, such as inflammatory bowel disease, tumors, appendicitis, Meckel's diverticulum, and others. Various imaging modalities commonly used for the gastrointestinal tract, including magnetic resonance imaging (MRI), positron emission tomography (PET) and single photon emission computed tomography (SPECT), and photoacoustic tomography (PAT) and multimodal imaging with mode overlap are summarized. These achievements in single and multimodal imaging provide useful guidance for improved diagnosis, staging, and treatment of the corresponding gastrointestinal diseases. The review evaluates the strengths and weaknesses of different imaging techniques and summarizes the development of imaging techniques used for diagnosing gastrointestinal ailments.

An Unexpected GIST Causing Life-Threatening Bleeding after an Elective Hernia Repair

Background  Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the alimentary tract. They are usually manifested by GI bleeding. Case Presentation  A 53-year-old male patient was admitted to the hospital for elective inguinal hernia repair. The patient did not have any history of GI symptoms in the past. A day after open inguinal hernia repair, the patient developed recurrent attacks of hematemesis resulting in hemodynamic instability and admission to the intensive care unit. An upper GI endoscopy identified a small bleeding gastric lesion. After multiple failed attempts to control the bleeding endoscopically, an emergency exploratory laparotomy was performed. An unexpected large fungating bleeding gastric mass was detected. The mass measured approximately 40 × 30 cm, and multiple peritoneal deposits were also discovered. A wedge resection of the anterior gastric wall along with the mass was performed. Histopathology revealed a high-grade (G2) GIST. Discussion  GISTs appear in variable sizes and may lead to a variety of complications including abdominal pain, GI obstruction, and bleeding. This case highlights the unexpected presentation and sudden bleeding of a large GIST in a totally asymptomatic patient undergoing elective hernia surgery. It also illustrates that GIST can be asymptomatic and grow to large sizes before developing clinical manifestations. Conclusion  The case report highlights a common complication of GIST with unexpected timing, immediately after routine hernia surgery.

Trends in Overall Survival among Patients Treated for Sarcoma at a Large Tertiary Cancer Center between 1986 and 2014

Sarcomas are relatively rare malignancies accounting for about 1% of all cancer diagnoses. Studies on sarcomas comprising large cohorts covering extended time periods are lacking. Therefore, this study aimed to evaluate the impact of demographic, behavioral, and clinical characteristics on overall survival (OS) among individuals diagnosed with soft tissue sarcoma (STS) or bone sarcoma at the Moffitt Cancer Center between 1986 and 2014. Unadjusted and multivariable Cox proportional hazard regression (CPHR) models were constructed to generate hazard ratios (HRs) and 95% confidence intervals (CIs) to evaluate associations between a range of demographic, behavioral, and clinical characteristics, and OS. Additionally, Kaplan-Meier survival curves, associated log-rank statistics, and adjusted CPHR models were generated by time periods based on the year of first contact (1986-1994, 1995-1999, 2000-2005, 2006-2010, 2011-2014) to evaluate for temporal differences in OS. Of the 2570 patients, 2037 were diagnosed with STS, whereas 533 were diagnosed with bone sarcoma. At the time of analysis, 50% of the population were alive. In multivariable analyses, we observed poorer survival for patients ≥ 40 years of age (HR = 1.54, 95% CI = 1.34-1.78), current smokers (HR = 1.18, 95% CI = 1.01-1.37), patients with metastasis (HR = 2.19, 95% CI = 1.95-2.47), and patients not receiving first-line surgery treatment (HR = 2.11, 95% CI = 1.82-2.45). We discovered limited improvements in OS over time among individuals diagnosed with STS or bone sarcomas with the exception of gastrointestinal stromal tumors (GIST), which showed a significant improvement in OS across time periods (p = 0.0034). Overall, we identified well-established characteristics associated with OS (e.g., metastasis) in addition to factors (e.g., smoking status) not previously reported to impact OS. Improvements in survival over time have been relatively modest, suggesting the need for improved therapeutic options, especially for those diagnosed with less frequent sarcomas.

An unusual and life-threatening presentation of a large GIST

Introduction

Case presentation

Clinical discussion

Conclusion

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Although an acute presentation of GIST is rare, it must be recognised early to prevent further morbidity and mortality.

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The overlap between the symptoms of GIST and other GI disorders could lead to an uncertain diagnosis and thus unfavourable outcome.

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Imaging modalities along with immunohistochemical studies have eased the diagnosis of GIST

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The characteristics of the tumor largely influence the treatment pathway.

Jejunal Gastrointestinal Stromal Tumor (GIST) as a Rare Cause of GI Bleed: A Case Report

Jejunal gastrointestinal stromal tumor (GIST) is a rare cause of recurrent gastrointestinal bleeding (GIB). Early diagnosis for patients with jejunal GIST is often challenging, which can lead to delays in treatment. We present a case of a 32-year-old male patient with persistent abdominal pain and hematemesis despite treatment for gastroesophageal reflux disease (GERD). Upon initial ER visit, CT result was consistent with intra-abdominal abscess and the patient underwent interventional radiology (IR) drainage. On a second ER visit three weeks later, CT showed a suspicious lesion in the small bowel. The patient underwent exploratory laparoscopy which revealed a mass in the jejunum. The lesion was resected successfully and pathology report confirmed the diagnosis of GIST with positive immunohistochemistry marker cluster of differentiation (CD)117. The patient was discharged with no complications post-operatively. In conclusion, recurrent GIB and unusual imaging findings should raise clinical suspicion for alternative causes for GIB, including tumors such as GIST.

Extremely Aggressive Mesenteric Extragastrointestinal Stromal Tumor: A Case Report and Literature Review

Gastrointestinal stromal tumors (GISTs) are rare tumors with increasing incidence. GIST is the most common mesenchymal tumor of the gastrointestinal tract involving the elderly population with a slow progression. It originates from the interstitial cells of Cajal. GISTs that develop outside the gastrointestinal tract and have no connections with the intestinal walls or serosal surfaces of the gastrointestinal tubular organs are referred to as extraintestinal gastrointestinal stromal tumors (EGISTs). They have similar morphological and immunohistological characteristics as GISTs. Here, we describe a unique case of an extremely aggressive mesenteric GIST in a 44-year-old African American male.

The patient presented to the hospital with complaints of generalized abdominal pain associated with 50-pound weight loss, decreased appetite, and constipation. He underwent computed tomography (CT) of the abdomen and pelvis which showed a large mass along the central mesentery measuring about 15 × 11 cm with adjacent metastatic nodal disease. He underwent a CT-guided biopsy of his abdominal mass with histopathology findings positive for c-kit (CD117) and discovered on GIST-1 (DOG-1) consistent with GIST. Based on TNM staging, his tumor was graded T4 with N1 given nodal involvement placing him as a stage IV. He was referred to an oncologist and was started on neoadjuvant therapy with imatinib. Mesenteric EGISTs, while rare, are known to have a worse prognosis compared to other EGISTs; hence, prompt action must be taken in aggressively treating these tumors. Factors such as mitotic index and tumor size affect the prognosis of mesenteric GISTs.

Nintedanib overcomes drug resistance from upregulation of FGFR signaling and imatinib-induced KIT mutations in gastrointestinal stromal tumors

Drug resistance remains a major challenge in the clinical treatment of gastrointestinal stromal tumours (GISTs). While acquired on‐target mutations of mast/stem cell growth factor receptor (KIT) kinase is the major resistance mechanism, activation of alternative signalling pathways may also play a role. Although several second‐ and third‐generation KIT kinase inhibitors have been developed that could overcome some of the KIT mutations conferring resistance, the low clinical responses and narrow safety window have limited their broad application. The present study revealed that nintedanib not only overcame resistance induced by a panel of KIT primary and secondary mutations, but also overcame ERK‐reactivation‐mediated resistance caused by the upregulation of fibroblast growth factor (FGF) activity. In preclinical models of GISTs, nintedanib significantly inhibited the proliferation of imatinib‐resistant cells, including GIST‐5R, GIST‐T1/T670I and GIST patient‐derived primary cells. In addition, it also exhibited dose‐dependent inhibition of ERK phosphorylation upon FGF ligand stimulation. In vivo antitumour activity was also observed in several xenograft GIST models. Considering the well‐documented safety and pharmacokinetic profiles of nintedanib, this finding provides evidence for the repurposing of nintedanib as a new therapy for the treatment of GIST patients with de novo or acquired resistance to imatinib.

Gastrointestinal stromal tumors diagnosis on multi-center endoscopic ultrasound images using multi-scale image normalization and transfer learning

BACKGROUND

Automated diagnosis of gastrointestinal stromal tumors' (GISTs) cancerization is an effective way to improve the clinical diagnostic accuracy and reduce possible risks of biopsy. Although deep convolutional neural networks (DCNNs) have proven to be very effective in many image classification problems, there is still a lack of studies on endoscopic ultrasound (EUS) images of GISTs. It remains a substantial challenge mainly due to the data distribution bias of multi-center images, the significant inter-class similarity and intra-class variation, and the insufficiency of training data.

OBJECTIVE

The study aims to classify GISTs into higher-risk and lower-risk categories.

METHODS

Firstly, a novel multi-scale image normalization block is designed to perform same-size and same-resolution resizing on the input data in a parallel manner. A dilated mask is used to obtain a more accurate interested region. Then, we construct a multi-way feature extraction and fusion block to extract distinguishable features. A ResNet-50 model built based on transfer learning is utilized as a powerful feature extractor for tumors' textural features. The tumor size features and the patient demographic features are also extracted respectively. Finally, a robust XGBoost classifier is trained on all features.

RESULTS

Experimental results show that our proposed method achieves the AUC score of 0.844, which is superior to the clinical diagnosis performance.

CONCLUSIONS

Therefore, the results have provided a solid baseline to encourage further researches in this field.

In-vitro study on the identification of gastrointestinal stromal tumor tissues using laser-induced breakdown spectroscopy with chemometric methods

Early-stage detection of tumors helps to improve patient survival rate. In this work, we demonstrate a novel discrimination method to diagnose the gastrointestinal stromal tumor (GIST) and its healthy formalin fixed paraffin embedded (FFPE) tissues by combining chemometric algorithms with laser-induced breakdown spectroscopy (LIBS). Chemometric methods which include partial least square discrimination analysis (PLS-DA), k-nearest neighbor (k-NN) and support vector machine (SVM) were used to build the discrimination models. The comparison of PLS-DA, k-NN and SVM classifiers shows an increase in accuracy from 94.44% to 100%. The comparison of LIBS signal between the healthy and infected tissues shows an enhancement of calcium lines which is a signature of the presence of GIST in the FFPE tissues. Our results may provide a complementary method for the rapid detection of tumors for the successful treatment of patients.

Incidental Gastrointestinal Stromal Tumors (GIST) During Laparoscopic Sleeve Gastrectomy Procedures: a Retrospective Study

PURPOSE

Gastrointestinal stromal tumors (GIST) are the most frequently occurring form of mesenchymal tumors in the gastrointestinal tract. Laparoscopic sleeve gastrectomy (LSG) is a commonly performed bariatric operation in which a portion of the gastric body and fundus is removed and sent for pathological examination. Increasingly, bariatric surgeons have incidentally identified neoplasms in the excised portion of the stomach. The aim of this study is to explore the incidence of GIST in obese patients undergoing LSG.

MATERIAL AND METHODS

This is a single-center, single-surgeon retrospective case series which included 305 obese patients who underwent LSG. All excised stomach specimens were sent for pathologic analysis.. In the case of pathologically verified GIST (n = 6; 1.97%), detailed analysis was performed.

RESULTS

In 305 LSG procedures, six cases of GIST (1.97%) were identified. The tumors were measured between 1 and 7 mm and were all low grade with negative resection margins. The mean BMI was 46.38 ± 3.94 kg/m2 (range: 41.61-51.77). The mean age at time of surgery was 55.33 ± 12.9 years (range: 37-73 years). All cases were asymptomatic and showed no evidence of metastatic disease.

CONCLUSION

The incidental rate of GIST in the excised portion of the stomach in our 305 obese patients who underwent LSG is 6/305 (1.97%). This adds relevant data to the overall goal of determining whether obesity is a risk factor for GIST. Radical surgical resection of these tumors with adequate disease-free margins performed on a low-grade malignancy serves as a definitive oncological treatment, especially when there is an intact pseudocapsule.

Multiple, large intra-abdominal cystic lesions and iron deficiency anaemia as the presenting symptoms of SDHD gastrointestinal stromal tumour (GIST) in a young sub-Saharan woman

We report the case of a 27-year-old female patient from sub-Saharan Africa who presented with non-specific abdominal complaints, iron deficiency anaemia and multiple, large intra-abdominal cystic lesions on imaging. The lesions appeared to be a most unusual presentation of gastrointestinal stromal tumour (GIST). GIST is a sarcomatous tumour that comprises only 0.2% of all gastrointestinal (GI) tumours; it is the most common mesenchymal malignancy of the GI tract. Our patient had the succinate dehydrogenase-deficient (SDHD) subtype, identified in some 5%-10% of patients with GIST only, commonly found in women and younger patients. The differential diagnosis of intra-abdominal cystic lesions is briefly discussed, including the relevance of a correct pathological diagnosis. This impacts medical and surgical management decisions, including predicting response to targeted therapy. Tyrosine kinase inhibitor therapy has been a breakthrough in the treatment of GISTs, although with extensive disease, and certainly in case of the SDHD subtype, long-term outcome remains disappointing.

Gastrointestinal Stromal Tumor: An Uncommon but Serious Cause of Gastrointestinal Bleeding

Gastrointestinal stromal tumors (GISTs) are rare tumors of the GI tract that can sometimes present as a gastrointestinal bleeding source. This report describes a patient presented with upper GI bleeding secondary to a gastric GIST, which was initially detected on endoscopy. The patient underwent surgical resection of the tumor and was started on adjuvant chemotherapy with imatinib. The patient’s postoperative course was complicated by an esophageal leak requiring re-exploratory laparotomy and esophageal stent placement. The stent was removed 5 weeks later and the patient remained stable for discharge after 60 days of inpatient care.

Skeletal muscle metastasis from a gastrointestinal stromal tumor: A case report

RATIONALE

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Common sites for metastasis are the liver and peritoneum, whereas skeletal muscle metastases are rare.

PATIENT CONCERNS

A 59-year-old man with skeletal muscle metastasis was diagnosed during a period of adjuvant imatinib therapy following the recurrence of GIST of the small intestine.

DIAGNOSIS

The patient was diagnosed with skeletal muscle metastasis of GIST based on immunohistochemistry and molecular pathology analysis results.

INTERVENTION

Extensive resection of the left thigh tumor was performed. The patient underwent whole-exome sequencing of tissue examination. The results suggest that resistance to imatinib may have been developed, and the patient was therefore administered sunitinib instead.

OUTCOMES

Complete remission was observed following sunitinib therapy.

LESSONS

In cases of skeletal muscle metastasis diagnosed during a period of adjuvant imatinib therapy following the recurrence of a GIST of the small intestine, whole exome sequencing may be used to discover more gene variations.

TN-USMA Net: Triple normalization-based gastrointestinal stromal tumors classification on multicenter EUS images with ultrasound-specific pretraining and meta attention

PURPOSE

Accurate quantification of gastrointestinal stromal tumors' (GISTs) risk stratification on multicenter endoscopic ultrasound (EUS) images plays a pivotal role in aiding the surgical decision-making process. This study focuses on automatically classifying higher-risk and lower-risk GISTs in the presence of a multicenter setting and limited data.

METHODS

In this study, we retrospectively enrolled 914 patients with GISTs (1824 EUS images in total) from 18 hospitals in China. We propose a triple normalization-based deep learning framework with ultrasound-specific pretraining and meta attention, namely, TN-USMA model. The triple normalization module consists of the intensity normalization, size normalization, and spatial resolution normalization. First, the image intensity is standardized and same-size regions of interest (ROIs) and same-resolution tumor masks are generated in parallel. Then, the transfer learning strategy is utilized to mitigate the data scarcity problem. The same-size ROIs are fed into a deep architecture with ultrasound-specific pretrained weights, which are obtained from self-supervised learning using a large volume of unlabeled ultrasound images. Meanwhile, tumors' size features are calculated from the same-resolution masks individually. Afterward, the size features together with two demographic features are integrated to the model before the final classification layer using a meta attention mechanism to further enhance feature representations. The diagnostic performance of the proposed method was compared with one radiomics-based method and two state-of-the-art deep learning methods. Four evaluation metrics, namely, the accuracy, the area under the receiver operator curve, the sensitivity, and the specificity were used to evaluate the model performance.

RESULTS

The proposed TN-USMA model achieves an overall accuracy of 0.834 (95% confidence interval [CI]: 0.772, 0.885), an area under the receiver operator curve of 0.881 (95% CI: 0.825, 0.924), a sensitivity of 0.844 (95% CI: 0.672, 0.947), and a specificity of 0.832 (95% CI: 0.762, 0.888). The AUC significantly outperforms other two deep learning approaches (p < 0.05, DeLong et al). Moreover, the performance is stable under different variations of multicenter dataset partitions.

CONCLUSIONS

The proposed TN-USMA model can successfully differentiate higher-risk GISTs from lower-risk ones. It is accurate, robust, generalizable, and efficient for potential clinical applications.

Prognostic Value of Bleeding in Gastrointestinal Stromal Tumors: A Meta-Analysis

Background:

Gastrointestinal bleeding is the most common clinical manifestation of gastrointestinal stromal tumor. It is of great significance to the prognosis of patients. But the results are controversial. The purpose of this study was to evaluate the relationship between gastrointestinal bleeding and clinical prognosis in patients with GIST.

Methods:

A systematic literature search was performed in Pumbed, Cochrane Library, EMBASE, ClinicalTrials.gov, CNKI, VIP and wanfang databases with the pattern of unlimited languages. 12 studies with 2781 individuals were included in the final analysis. The overall survival (OS), recurrence-free survival/disease-free survival (RFS/DFS) and related factors affecting bleeding in patients with gastrointestinal stromal tumor (GIST) were extracted. Hazard ratio (HR) and 95% confidence interval (CI) were used for in the meta-analysis.

Results:

A total of 12 articles were included in the study, including 2781 patients with GIST, including 845 patients with gastrointestinal bleeding. The OS of GIST patients with gastrointestinal bleeding was significantly worse (HR = 2.54, 95% CI = 1.13-5.73, P = 0.025). But there was no significant difference in RFS between gastrointestinal bleeding patients and non-bleeding patients (HR = 1.35, 95% CI = 0.70-2.61, P = 0.371). Further analysis of the related factors of GI bleeding in GIST patients was observed, besides the aging factor (HR = 1.02, 95% CI = 0.69-1.50, P = 0.929), Small intestinal stromal tumor (HR = 0.56, 95% CI = 0.41-0.76, P < 0.001), tumor diameter ≥ 5 cm (HR = 2.09, 95% CI = 1.20-3.63, P = 0.009), Mitotic index ≥ 5/50 HPF (HR = 1.66, 95% CI = 1.11-2.49, P = 0.014) and tumor rupture (HR = 2.04, 95% CI = 1.0-3.82, P = 0.026) all increased the risk of GI bleeding in patients with GIST.

Conclusions:

The OS of GIST patients with GI bleeding was worse than non-GI bleeding, but had no significant effect on RFS. Nevertheless the aging factor, the location of GIST in the small intestine, tumor diameter ≥ 5 cm, Mitotic index ≥ 5/50 HPF and tumor rupture all increased the risk of GI bleeding in patients with GIST.

Refractory hypoglycaemia in a localised gastrointestinal stromal tumour: Case report

INTRODUCTION

GIST and NICTH are mesenchymal in origin however there are very few reports of GIST associated with NICTH which is a para neoplastic syndrome, generally diagnosed when a tumour induced hypoglycaemia is noted.

CASE PRESENTATION

A 46 years old female with prime complain of awareness of a mass in the upper abdomen was admitted for evaluation and further management. Detailed investigation revealed the mass to be gastrointestinal stromal tumour. On the day of admission patient was found to be hypoglycaemic which didn't resolve even after 10% glucose infusion. A growth hormone releasing peptide-2 (GHRP-2) assay was carried out which showed an excessive reaction of basal growth hormone however corticotropin releasing hormone (CRH) tests were within normal limits. She was suspected to be Non Islet cell tumour hypoglycaemia (NICTH) and hypoglycaemia resolved upon administering dexamethasone. Later she underwent chemotherapy and surgical resection after which her blood sugar levels were within normal limits.

DISCUSSION

Expression of big IGF-II on the surface of GIST be it metastatic or nonmetastatic can cause refractory hypoglycaemia and can be fatal if left untreated.

CONCLUSION

Clinicians should be aware of refractory hypoglycaemia in patients with large GIST's as glucocorticoid therapy may prove to be extremely useful and lifesaving even before considering any forms of definitive management of the tumour.

Familial wild-type gastrointestinal stromal tumour in association with germline truncating variants in both SDHA and PALB2

Gastrointestinal stromal tumour (GIST) is a mesenchymal neoplasm arising in the gastrointestinal tract. A rare subset of GISTs are classified as wild-type GIST (wtGIST) and these are frequently associated with germline variants that affect the function of cancer predisposition genes such as the succinate dehydrogenase subunit genes (SDHA, SDHB, SDHC, SDHD) or NF1. However, despite this high heritability, familial clustering of wtGIST is extremely rare. Here, we report a mother–son diad who developed wtGIST at age 66 and 34 years, respectively. Comprehensive genetic testing revealed germline truncating variants in both SDHA (c.1534C>T (p.Arg512*)) and PALB2 (c.3113G>A (p.Trp1038*)) in both affected individuals. The mother also developed breast ductal carcinoma in-situ at age 70 years. Immunohistochemistry and molecular analysis of the wtGISTs revealed loss of SDHB expression and loss of the wild-type SDHA allele in tumour material. No allele loss was detected at PALB2 suggesting that wtGIST tumourigenesis was principally driven by succinate dehydrogenase deficiency. However, we speculate that the presence of multilocus inherited neoplasia alleles syndrome (MINAS) in this family might have contributed to the highly unusual occurrence of familial wtGIST. Systematic reporting of tumour risks and phenotypes in individuals with MINAS will facilitate the clinical interpretation of the significance of this diagnosis, which is becoming more frequent as strategies for genetic testing for hereditary cancer becomes more comprehensive.

Optimal Avapritinib Treatment Strategies for Patients with Metastatic or Unresectable Gastrointestinal Stromal Tumors

BACKGROUND

Avapritinib, a novel inhibitor of KIT/PDGFRA, is approved in the U.S. for the treatment of adults with PDGFRA exon 18-mutant unresectable or metastatic gastrointestinal stromal tumors (U/M GISTs). We assessed the safety of avapritinib and provide evidence-based guidance on management of avapritinib-associated adverse events (AEs), including cognitive effects and intracranial bleeding.

MATERIALS AND METHODS

We performed a post hoc analysis of data from a two-part, single-arm dose escalation/expansion phase I study (NAVIGATOR; NCT02508532) in patients with U/M GISTs treated with oral avapritinib 30-600 mg once daily. The primary endpoints were safety and tolerability; the impact of dose modification (interruption and/or reduction) on progression-free survival (PFS) was a secondary endpoint. Efficacy analyses were limited to patients who started avapritinib at 300 mg (approved dose).

RESULTS

Of 250 patients enrolled in the study, 74.0% presented with KIT mutation and 24.8% presented with PDGFRA exon 18-mutation; 66.8% started avapritinib at 300 mg. The most common treatment-related AEs (any grade) were nausea (59.2%), fatigue (50.0%), periorbital edema (42.0%), anemia (39.2%), diarrhea (36.0%), vomiting (36.0%), and increased lacrimation (30.8%). No treatment-related deaths occurred. Among 167 patients starting on 300 mg avapritinib, all-cause cognitive effects rate (grade 1-2) was 37.0% in all patients and 52.0% in patients ≥65 years. Cognitive effects improved to a lower grade more quickly with dose modification (1.3-3.1 weeks) than without (4.9-7.6 weeks). Median PFS was 11.4 months with dose modification and 7.2 months without.

CONCLUSION

Tolerability-guided dose modification of avapritinib is an effective strategy for managing AEs in patients with GISTs.

IMPLICATIONS FOR PRACTICE

Early recognition of adverse events and tailored dose modification appear to be effective approaches for managing treatment-related adverse events and maintaining patients on avapritinib. Dose reduction does not appear to result in reduced efficacy. Patients' cognitive function should be assessed at baseline and monitored carefully throughout treatment with avapritinib for the onset of cognitive adverse events. Dose interruption is recommended at the first sign of any cognitive effect, including grade 1 events.

Preoperative Diagnosis Failure for a Rare Gastric Collision Tumor: A Case Report

Gastrointestinal stromal tumors (GISTs) are common mesenchymal tumors of the gastrointestinal tract (GIT), usually occur as a solitary neoplasm. Inflammatory florid polyp (IFP) is a solitary rare benign lesion of the gastrointestinal tract, mainly occur in the gastric antrum, whose atypical presentation can mimic GISTs or other malignant tumors, therefore the synchronous occurrence of GISTs and IFP is extremely rare. We had a case of a 58-year-old man that was presented with recurrent epigastric pain and recurrent melena. Upper endoscopic examination revealed a large polypoid antrum polyp measured 7 cm at greatest dimension with focal ulceration. Clinical and radiological features did not reach the definite diagnosis until histopathological evaluation with immunohistochemical analysis was performed. Surgical intervention is recommended and partial gastrectomy was done with wide resection margins. Histological examination revealed two distinct GISTs and IFP parts presenting a collision tumor that showed spindle and epitheloid cells consistent with GISTs with histological features of florid polyp showed a characteristic perivascular onion-skin arrangement of spindle cells with dense chronic inflammatory infiltrate including eosinophils and lymphocytes. Immunohistochemical studies have been done and revealed an association between GISTs and IFP. To the best of our knowledge, this is the first case of a collision tumor consisting of a GIST and an IFP arising in the stomach. In conclusion, the gastrointestinal stromal tumor is the comments mesenchymal tumor of GIT and IFP is a rare benign lesion of GIT therefore association between GIST and IFP as a collision tumor is extremely rare.

Efficacy evaluation of nilotinib treatment in different genomic subtypes of gastrointestinal stromal tumors: A meta-analysis and systematic review

Nilotinib has been used as a third-line drug for gastrointestinal stromal tumors (GISTs) after a failure of sunitinib. In this study, we aimed to evaluate the efficacy of nilotinib in different genomic subtypes of GISTs. We searched the English articles through EMBASE, Cochrane Library and PubMed Database regarding to the use of nilotinib on GISTs, which published up to February 15, 2019. Inclusion criteria were: GISTs patients received nilotinib in a clinical trial and had detailed genetic subtype records (such as KIT exon 9, KIT exon 11, or PDGFRA mutations, or wild-type). The clinical benefit rate was used to assess the efficacy of nilotinib. A total of 3 studies involving 218 GISTs were included in this meta-analysis. The overall OR (KIT group vs WT group) was 3.26 (95% CI: 1.14-9.28; P = 0.027, P_{heterogeneity} = 0.613). The overall OR in KIT exon 11 group vs WT group was 5.30 (95% CI: 1.79-15.68; P = 0.003, P_{heterogeneity} = 0.409). The overall OR in KIT exon 9 group vs WT group was 0.13 (95% CI: 0.02-0.86; P = 0.035, P_{heterogeneity} = 0.229). The overall OR in KIT exon 11 group vs exon 9 group was 9.96 (95% CI: 0.39-254.66; P < 0.0001, P_{heterogeneity} = 0.024). Different genotypes of GISTs showed different responses to nilotinib, and KIT exon 11-mutant GISTs mostly benefited from nilotinib, followed by KIT exon 9-mutant or WT one.

Gastrointestinal Stromal Tumors (GISTs): Novel Therapeutic Strategies with Immunotherapy and Small Molecules

Gastrointestinal stromal tumors (GISTs) are the most common types of malignant mesenchymal tumors in the gastrointestinal tract, with an estimated incidence of 1.5/100.000 per year and 1–2% of gastrointestinal neoplasms. About 75–80% of patients have mutations in the KIT gene in exons 9, 11, 13, 14, 17, and 5–10% of patients have mutations in the platelet-derived growth factor receptor a (PDGFRA) gene in exons 12, 14, 18. Moreover, 10–15% of patients have no mutations and are classified as wild type GIST. The treatment for metastatic or unresectable GISTs includes imatinib, sunitinib, and regorafenib. So far, GIST therapies have raised great expectations and offered patients a better quality of life, but increased pharmacological resistance to tyrosine kinase inhibitors is often observed. New treatment options have emerged, with ripretinib, avapritinib, and cabozantinib getting approvals for these tumors. Nowadays, immune checkpoint inhibitors form a new landscape in cancer therapeutics and have already shown remarkable responses in various tumors. Studies in melanoma, non-small-cell lung cancer, and renal cell carcinoma are very encouraging as these inhibitors have increased survival rates. The purpose of this review is to present alternative approaches for the treatment of the GIST patients, such as combinations of immunotherapy and novel inhibitors with traditional therapies (tyrosine kinase inhibitors).

Individualized Management of Blood Concentration in Patients with Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor, and surgical resection is the first choice for the treatment of the disease, but since the advent of tyrosine kinase inhibitors (TKIs) such as imatinib (IM), the prognosis of the disease has undergone revolutionary changes. According to the current version of the guidelines, most GIST patients receive a fixed dose without taking into account their own individual differences, resulting in a wide difference in blood concentration, adverse reactions and prognosis. With more studies on the relationship between blood drug concentrations and prognosis, the concept of individualized therapy has been paid more attention by researchers. Therapeutic drug monitoring (TDM) has also been made available for the research field of GIST targeted therapy. How to reduce the incidence of drug resistance and adverse reactions in patients with GISTs has become the focus of the current research. This article reviews the common monitoring methods and timing of TKIs blood concentration, the reasonable range of blood drug concentration, the toxic or adverse effects caused by high blood drug concentration, some possible factors affecting blood drug concentration and recent research progress, in order to discuss and summarize the treatment strategy of individual blood drug concentration, improve the prognosis of patients and reduce the adverse effects as much as possible.

Get the GIST: A Case Study of Detection and Treatment of Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GISTs) are soft tissue sarcomas that can occur anywhere in the GI tract. There are roughly 4,000 to 6,000 cases diagnosed in the United States annually. GISTs are often asymptomatic early on and can evade detection, occasionally resulting in malignancy. Due to their insidious growth and location, it is suspected that they are more common than currently reported. It is important to know how difficult it is to identify a GIST and the various methods to treat it in a patient. Our case presents a 62-year-old male with incidental findings of multiple GISTs during workup for kidney stones. The patient was fortunate that these tumors were detected before developing into a greater health concern and this case highlights the insidious nature with which they develop.

Molecular Modeling Study of c-KIT/PDGFRα Dual Inhibitors for the Treatment of Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GISTs) are the most common Mesenchymal Neoplasm of the gastrointestinal tract. The tumorigenesis of GISTs has been associated with the gain-of-function mutation and abnormal activation of the stem cell factor receptor (c-KIT) and platelet-derived growth factor receptor alpha (PDGFRα) kinases. Hence, inhibitors that target c-KIT and PDGFRα could be a therapeutic option for the treatment of GISTs. The available approved c-KIT/PDGFRα inhibitors possessed low efficacy with off-target effects, which necessitated the development of potent inhibitors. We performed computational studies of 48 pyrazolopyridine derivatives that showed inhibitory activity against c-KIT and PDGFRα to study the structural properties important for inhibition of both the kinases. The derivative of phenylurea, which has high activities for both c-KIT (pIC₅₀ = 8.6) and PDGFRα (pIC₅₀ = 8.1), was used as the representative compound for the dataset. Molecular docking and molecular dynamics simulation (100 ns) of compound 14 was performed. Compound 14 showed the formation of hydrogen bonding with Cys673, Glu640, and Asp810 in c-KIT, and Cys677, Glu644, and Asp836 in PDGFRα. The results also suggested that Thr670/T674 substitution in c-KIT/PDGFRα induced conformational changes at the binding site of the receptors. Three-dimensional quantitative structure-activity relationship (3D-QSAR) models were developed based on the inhibitors. Contour map analysis showed that electropositive and bulky substituents at the para-position and the meta-position of the benzyl ring of compound 14 was favorable and may increase the inhibitory activity against both c-KIT and PDGFRα. Analysis of the results suggested that having bulky and hydrophobic substituents that extend into the hydrophobic pocket of the binding site increases the activity for both c-KIT and PDGFRα. Based on the contour map analysis, 50 compounds were designed, and the activities were predicted. An evaluation of binding free energy showed that eight of the designed compounds have potential binding affinity with c-KIT/PDGFRα. Absorption, distribution, metabolism, excretion and toxicity (ADMET) and synthetic feasibility tests showed that the designed compounds have reasonable pharmaceutical properties and synthetic feasibility. Further experimental study of the designed compounds is recommended. The structural information from this study could provide useful insight into the future development of c-KIT and PDGFRα inhibitors.

Development of a Malignancy Potential Binary Prediction Model Based on Deep Learning for the Mitotic Count of Local Primary Gastrointestinal Stromal Tumors

Objective

The mitotic count of gastrointestinal stromal tumors (GIST) is closely associated with the risk of planting and metastasis. The purpose of this study was to develop a predictive model for the mitotic index of local primary GIST, based on deep learning algorithm.

Materials and Methods

Abdominal contrast-enhanced CT images of 148 pathologically confirmed GIST cases were retrospectively collected for the development of a deep learning classification algorithm. The areas of GIST masses on the CT images were retrospectively labelled by an experienced radiologist. The postoperative pathological mitotic count was considered as the gold standard (high mitotic count, > 5/50 high-power fields [HPFs]; low mitotic count, ≤ 5/50 HPFs). A binary classification model was trained on the basis of the VGG16 convolutional neural network, using the CT images with the training set (n = 108), validation set (n = 20), and the test set (n = 20). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated at both, the image level and the patient level. The receiver operating characteristic curves were generated on the basis of the model prediction results and the area under curves (AUCs) were calculated. The risk categories of the tumors were predicted according to the Armed Forces Institute of Pathology criteria.

Results

At the image level, the classification prediction results of the mitotic counts in the test cohort were as follows: sensitivity 85.7% (95% confidence interval [CI]: 0.834–0.877), specificity 67.5% (95% CI: 0.636–0.712), PPV 82.1% (95% CI: 0.797–0.843), NPV 73.0% (95% CI: 0.691–0.766), and AUC 0.771 (95% CI: 0.750–0.791). At the patient level, the classification prediction results in the test cohort were as follows: sensitivity 90.0% (95% CI: 0.541–0.995), specificity 70.0% (95% CI: 0.354–0.919), PPV 75.0% (95% CI: 0.428–0.933), NPV 87.5% (95% CI: 0.467–0.993), and AUC 0.800 (95% CI: 0.563–0.943).

Conclusion

We developed and preliminarily verified the GIST mitotic count binary prediction model, based on the VGG convolutional neural network. The model displayed a good predictive performance.

Skin Metastasis of Gastrointestinal Stromal Tumors: A Case Series and Literature Review

Background

Gastrointestinal stromal tumors (GISTs) extremely and rarely metastasize to the skin, and such metastases have not been well characterized.

Methods

Retrospective analysis of clinicopathological data of patients with skin metastasis of a GIST (SM-GIST) admitted to Xiangya Hospital (Changsha, Hunan, China) and literature review were conducted.

Results

Including our 4 cases, a total of 17 cases have been reported to date. The mean age of the patients was 55.4 years (29~70 years) and there was not sex predominance (male 10 and female 7). Primary tumors were often located in the stomach (n=9), duodenum (n=2) and small bowel (n=2). Meanwhile, SM-GIST mainly occurred in head and face (n=6), extremities (n=6), followed by abdomen wall (n=5), back (n=3) and chest (n=2). Mutation analysis revealed that the frequency of wild-type GIST (WT-GIST), exon 9, 11 and 13 mutations was 6, 1, 4 and 1, respectively. The average time to SM-GIST was 4.22 years, specifically 4.59 years in gastric and 3.8 years in non-gastric. Moreover, for the resection only group (including chemotherapy), such average time was 3.63 years, while for the combined group (resection and tyrosine kinase inhibitors (TKIs)), it was about 4.74 years. The mean survival was approximately 6.2 years. However, after the diagnosis of SM-GIST, survival was only about 1.69 years.

Conclusion

SM-GIST is a rare malignant condition. Non-gastric GIST, surgery without TKIs, high invasiveness and tumor burden, and molecular subtype (mutation in exon 9, 11 and wild-type) may be conducive to the development of SM-GIST. Additionally, it is also a sign of poor prognosis.

Gastrointestinal stromal tumor of the excluded stomach after Roux-en-Y gastric bypass: A case report and literature review

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This is the second reported case of GIST post-RYGB.

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GISTs generally present good prognosis after surgical resection.

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The case reported after RYGB did not present the patient follow-up.

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The case reported after gastric banding presented recurrence 3 years after resection.

Background

Gastric cancer is an extremely rare condition to occur after bariatric surgery, and most of the reported cases are adenocarcinomas. Regarding gastrointestinal stromal tumors (GISTs), there are only two reported cases occurring after bariatric surgery (one after gastric banding and the other following Roux-en-Y gastric bypass (RYGB)).

Case presentation

A 48-year-old woman with previous history of obesity and type 2 diabetes, treated with a Roux-en-Y gastric bypass 2 years earlier, was referred to our center due to complains of diffuse abdominal pain and distension associated with asthenia. Magnetic resonance imaging showed a cystic-solid mass located in the right hypochondrium, measuring 19.5 × 13.5 × 16 cm, suggesting the diagnosis of a retroperitoneal tumor. Based on these findings, a laparotomy, evidencing that the larger cystic-solid tumor was originating from the excluded stomach post-RYGB. The gastrectomy of the excluded stomach was performed aside with a conventional cholecystectomy. Histopathology and immunohistochemistry confirmed to be a gastric GIST with epithelioid cells. Currently, 12 months after surgery, the patient presents no signs of recurrence.

Conclusion

This is the second case of gastric GIST occurring after RYGB to be reported in the literature.

Metabolic behavior and prognostic role of pretreatment 18F-FDG PET/CT in gist

AIM

The metabolic behavior and the prognostic value of ¹⁸ F-FDG-PET/CT in gastrointestinal stromal tumor (GIST) is not well investigated. The aim of this study was to analyze the metabolic behavior of GIST and the prognostic role of pretreatment PET/CT features.

METHODS

In this retrospective study, we included 35 patients with a diagnosis of GIST who underwent a pretreatment ¹⁸ F-FDG-PET/CT scan. We analyzed PET images visually and semiquantitatively by measuring several metabolic parameters as the maximum standardized uptake value corrected for body weight (SUVbw), for lean body mass (SUVlbm), for body surface area (SUVbsa), metabolic tumor volume (MTV) and total lesion glycolysis (TLG). The Kaplan-Meier method was used to measure the progression free survival (PFS) and overall survival curves.

RESULTS

Twenty-nine (82%) patients showed a positive ¹⁸ F-FDG-PET/CT, whereas the remaining 6 had no hypermetabolic lesions. ¹⁸ F-FDG-avidity was significantly related with mitotic index, tumor stage and tumor risk group. Instead, semiquantitative PET/CT parameters correlated only with tumor risk group. Disease progression occurred in 16 patients whereas death in seven. ¹⁸ F-FDG-avidity, MTV and TLG were the only variables significantly associated with PFS.

CONCLUSION

An 82% rate of PET avidity in GIST was found and it was correlated with stage, tumor risk group and mitotic index. Only baseline ¹⁸ F-FDG-avidity, MTV and TLG were independently correlated with PFS.

Plocabulin, a novel tubulin inhibitor, has potent antitumor activity in patient-derived xenograft models of gastrointestinal stromal tumors

The majority of patients with gastrointestinal stromal tumors (GIST) eventually become resistant with time due to secondary mutations in the driver receptor tyrosine kinase. Novel treatments that do not target these receptors may therefore be preferable. For the first time, we evaluated a tubulin inhibitor, plocabulin, in patient-derived xenograft (PDX) models of GIST, a disease generally considered to be resistant to cytotoxic agents. Three PDX models of GIST with different KIT genotype were generated by implanting tumor fragments from patients directly into nude mice. We then used these well characterized models with distinct sensitivity to imatinib to evaluate the efficacy of the novel tubulin inhibitor. The efficacy of the drug was assessed by volumetric analysis of the tumors, histopathology, immunohistochemistry and Western blotting. Plocabulin treatment led to extensive necrosis in all three models and significant tumor shrinkage in two models. This histological response can be explained by the drug's vascular-disruptive properties, which resulted in a shutdown of tumor vasculature, reflected by a decreased total vascular area in the tumor tissue. Our results demonstrated the in vivo efficacy of the novel tubulin inhibitor plocabulin in PDX models of GIST and challenge the established view that GIST are resistant to cytotoxic agents in general and to tubulin inhibitors in particular. Our findings provide a convincing rationale for early clinical exploration of plocabulin in GIST and warrant further exploration of this class of drugs in the management of this common sarcoma subtype.

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First study evaluating a tubulin inhibitor in patient-derived xenograft models of gastro-intestinal stromal tumors

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Plocabulin, a novel tubulin inhibitor, has efficacy independant of KIT genotype

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Plocabulin induced extensive, central tumor necrosis, mainly through its antiangiogenic properties.

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Our results challenge the established view that gastro-intestinal stromal tumors are resistant to cytotoxic agents.

Prognostic Indicators for Gastrointestinal Stromal Tumors: A Review

Gastrointestinal stromal tumors (GISTs) are potentially malignancies that can occur anywhere in the digestive tract. Tyrosine kinase inhibitors (TKIs) such as imatinib have proven effective since the discovery of KIT and PDGFRA. The current version of NCNN, ESMO and EURACAN guidelines recognized that the three main prognostic factors are the mitotic rate, tumor size and tumor site. In addition, tumor rupture is also recognized as an independent risk factor. However, recent evidence shows that various types of gene mutations are associated with prognosis, and influencing factors such as gastrointestinal bleeding and high Ki67 index have been associated with poor prognosis. It shows that the current risk classification is still insufficient and controversial. With the emergence of more and more lack mutation in KIT/PDGFRA GISTs (KIT/PDGFRA wild-type GISTs) or drug resistance genes, primary and secondary drug resistance problems are caused, which makes the treatment of late or metastatic GIST face challenges. Therefore, this article will review the clinicopathological characteristics of GIST, the special molecular subtypes and other factors that may affect prognosis. We will also explore reliable prognostic markers for better postoperative management and improve the prognosis of patients with GIST.

Role of non-coding RNAs in pathogenesis of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are considered the model solid malignancies of targeted therapy after the discovery of imatinib effectiveness against their tyrosine kinase inhibitors. Non-coding RNAs are molecules with no protein coding capacity that play crucial role to several biological steps of normal cell proliferation and differentiation. When the expression of these molecules found to be altered it seems that they affect the process of carcinogenesis in multiple ways, such as proliferation, apoptosis, differentiation, metastasis, and drug resistance. This review aims to provide an overview of the latest research papers and summarize the current evidence about the role of non-coding RNAs in pathogenesis of GISTs, including their potential clinical applications.

Association of Papillary Thyroid Carcinoma with GIST-a Case Series

Gastrointestinal stromal tumours (GIST) are the most common gastrointestinal mesenchymal tumours of the gastrointestinal tract. They are diagnosed by the expression of markers like CD 117, CD 34, DOG-1 and PDGFRA. The identification of these mutations has resulted in a better understanding of their oncogenic mechanisms. Few studies have shown the high incidence of a second malignancy including papillary thyroid cancer (PTC) in known patients of GIST. Literature review on pathogenesis of GIST and PTC showed that PTC targeting Protein Kinase C theta (PKCθ) plays role in both PTC and GIST. Further studies have also shown that, apart from somatic and familial gastrointestinal stromal tumours, PDGFRA is associated with many other malignancies including PTC. These studies explain the common genetic pathway involved in the development of GIST and PTC in same patient. In spite of common genetic association between GIST and other malignancies, none of the standard protocols recommends screening for second malignancy. In this article, we present the details of four patients who had associated GIST and PTC at the same time or developed during follow-up.