Clinical practice guideline for accurate diagnosis and effective treatment of gastrointestinal stromal tumor in Korea

The Feasibility and Safety of the Clip-and-Snare Method with a Prelooping Technique for Gastric Submucosal Tumors Removal: A Single-Center Experience (with Video)

AIM

This study compared the efficacy and safety of endoscopic submucosal dissection (ESD) combined with clip-and-snare method and a prelooping technique (CSM-PLT) with ESD alone for the treatment of gastric submucosal tumors (gSMTs).

METHODS

We retrospectively enrolled a matched group of 86 patients who received ESD combined with CSM-PLT or ESD alone from July 2010 to July 2020. The primary outcomes included complete resection, en bloc resection, and R0 resection.

RESULTS

Eighty-six patients with gSMTs were enrolled in ESD combined with CSM-PLT group and ESD group, respectively. There were no significant differences in gender, age, tumor size, tumor location, and tumor origin between the two groups. The complete resection, en bloc resection, and R0 resection rates were comparable between two groups (P=1, P=0.31, and P=0.25, respectively). There were no significant differences in terms of hospital stays, hospitalization cost, postoperative complications, and residual rate (P=0.42, P=0.74, P=0.65, and P=1, respectively) between the two groups. However, the ESD combined with CSM-PLT was associated with a shorter procedure duration and fewer intraoperative complications (P < 0.001 and P=0.024, respectively). In addition, the incidence of intraoperative bleeding in ESD combined with CSM-PLT group was significantly lower than that in ESD group (P=0.04).

CONCLUSION

Both ESD combined with CSM-PLT and ESD were effective and safe modalities for the treatment of gSMTs. However, ESD combined with CSM-PLT was associated with a shorter procedure duration and fewer intraoperative complications.

Diagnostic and Therapeutic Challenges in the Management of Acute Massive Overt Bleeding of Jejunal Gastrointestinal Stromal Tumours: Case Series

INTRODUCTION

Jejunal gastrointestinal stromal tumours (GIST) are rare mesenchymal tumours. Acute massive overt bleeding from jejunal GIST is very rare and poses both diagnostic and therapeutic challenges in emergent conditions.

METHODS

A case series with retrospective analysis of prospectively maintained database of patients presenting with acute massive overt bleeding secondary to histologically proven jejunal GIST was done. Clinical characteristics, endoscopic and imaging diagnostic features, histological findings, surgical procedures and outcomes in these patients were studied.

RESULTS

Three patients were included in this case series. Mean age of presentation was 49.0 years with two male and one female patient. All three patients presented with melena and hemodynamic instability, resuscitated with adequate blood transfusions. Routine endoscopic assessment were inconclusive. Multiphasic Computed Tomographic Angiography (CTA) revealed hypodense hypervascular mass in jejunum in all three patients. One patient was unresponsive to blood transfusion and underwent emergency exploratory laparotomy. One patient underwent laparoscopic resection and reconstruction. Mean length of hospital stay was 5.3 days. Histopathological examination confirmed jejunal GIST in all three patients with microscopically negative resection margins. Two patients were disease free till 18-month follow-up and the one patient lost to follow-up after 1 year.

CONCLUSION

Multiphasic CTA is a single-step diagnostic tool for localisation of bleed and assessment of tumour characteristics in emergent conditions. Surgical resection is the mainstay of treatment for both control of bleed and to provide oncologically clear resection margins.

The Pathologic Confirmation in Subepithelial Tumors

Background/Aims: Subepithelial tumors (SETs) are small, mostly asymptomatic lesions with normal overlying mucosa, usually identified incidentally on endoscopy. The aim of this study was to evaluate the pathologic diagnosis of SETs, and to assess the diagnostic yield and impact of endoscopic submucosal dissection (ESD) biopsy on the management of patients with SETs.Materials and Methods: We included 52 subepithelial lesions in this study during the study period. Inclusion criteria included size of the SET >2 cm, and a gastrointestinal stromal tumor (GIST) that cannot be excluded using EUS. We performed an endoscopic biopsy of each SET using the ESD technique.Results: The mean diameter of the lesions was 24.15±6.0 mm. The diagnostic yield of this method was 96.15%. Among the 52 participants, 45 were located in the stomach, four in the esophagus, and three in the duodenum. The pathologic diagnoses included: 17 leiomyomas, 13 GISTs, 11 ectopic pancreases, two carcinomas, two inflammatory fibroid polyps, two Brunner’s gland hyperplasia, two lipomas, one glomus tumor, and two remained undiagnosed. The mean duration of the procedure was 13.44±2.41 minutes. Three complications were associated with the procedure.Conclusions: Deep biopsy via ESD is useful in determining the histopathologic nature of SETs. This method minimizes the need for unnecessary surgery in benign SETs.

Diagnosis and Treatment of Duodenal Gastrointestinal Stromal Tumors

The diagnostic value of different noninvasive diagnostic modalities and the endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) reliability of duodenal gastrointestinal stromal tumors (GISTs) are ambiguous in the present studies.

Rare Occurrence of Microsatellite Instability in Gastrointestinal Stromal Tumors

Background and Objectives: This study aimed to objectively determine microsatellite instability (MSI) status using a next-generation sequencing (NGS)-based MSI panel and to resolve the discrepancy regarding whether or not MSI is a rare phenomenon, irrespective of diverse genomic alterations in gastrointestinal stromal tumors (GISTs). Materials and Methods: Genomic DNA was subjected to MSI panel sequencing using an Ion AmpliSeq Microsatellite Instability Assay, as well as to cancer gene panel sequencing using an Oncomine Focus DNA Assay. Results: All of our GIST patients showed microsatellite-stable (MSS) status, which confirmed that MSI status did not affect the molecular pathogenesis of GIST. The KIT gene (79%, 38/48) was the most frequently mutated gene, followed by the PDGFRA (8%, 4/48), PIK3CA (8%, 4/48), and ERBB2 (4%, 2/48) mutations. KIT exon 11 mutant patients were more favorable in responding to imatinib than those with exon 9 mutant or wild-type GISTs, and compared to non-KIT exon 11 mutant GISTs (p = 0.041). The NGS-based MSI panel with MSICall confirmed a rare phenomenon of microsatellite instability in GISTs irrespective of diverse genomic alterations. Conclusion: Massively parallel sequencing can simultaneously provide the MSI status as well as the somatic mutation profile in a single test. This combined approach may help us to understand the molecular pathogenesis of GIST carcinogenesis and malignant progression.

Imatinib in combination with phosphoinositol kinase inhibitor buparlisib in patients with gastrointestinal stromal tumour who failed prior therapy with imatinib and sunitinib: a Phase 1b, multicentre study

Background

The majority of patients with advanced gastrointestinal stromal tumours (GISTs) develop resistance to imatinib and sunitinib, the standard of care for these patients. This study evaluated the combination of buparlisib, an oral phosphoinositide 3-kinase (PI3K) inhibitor, with imatinib in patients with advanced GIST, who have failed prior therapy with imatinib and sunitinib.

Methods

This Phase 1b, multicentre, open-label study aimed to determine the maximum tolerated dose (MTD) and/or a recommended Phase 2 dose of buparlisib in combination with 400 mg of imatinib through a dose-escalation part and a dose-expansion part, and also evaluated the clinical profile of the combination.

Results

Sixty patients were enrolled, including 25 in the dose-escalation part and 35 in the dose-expansion part. In the combination, MTD of buparlisib was established as 80 mg. No partial or complete responses were observed. The estimated median progression-free survival was 3.5 months in the expansion phase. Overall, 98.3% of patients had treatment-related adverse events (AEs), including 45% with grade 3 or 4 AEs.

Conclusions

Buparlisib in combination with imatinib provided no additional benefit compared with currently available therapies. Due to the lack of objective responses, further development of this combination was not pursued for third-line/fourth-line advanced/metastatic GIST.

Trial registration number

NCT01468688.

Life-threatening bleeding with intussusception due to gastrointestinal stromal tumor: a case report

Background

Massive intraluminal bleeding requires urgent intervention and management. However, the source of bleeding on the small intestine is difficult to determine. Intestinal tumor with intussusception is a rare and normally not an urgent condition. Herein, we present a rare case of intestinal intussusception with massive bleeding due to jejunal gastrointestinal stromal tumor (GIST) that required emergency surgical treatment.

Case presentation

A 51-year-old male was admitted to the emergency department complaining of abdominal pain and acute hematochezia. Esophagogastroduodenoscopy (EGD) and colonoscopy could not determine the source of the bleeding site. Abdominal pelvic computed tomography (AP-CT) revealed GIST with intussusception, strongly suggestive of distal jejunal bleeding. Unresponsive transfusion with low blood pressure and continuous hematochezia led to emergency laparotomy. GIST, which was the leading point for intussusception, was located in the jejunum and showed mucosal ulceration of approximately 3.5 cm in diameter. Following resection and functional anastomosis, histology revealed a GIST with low mitotic count (< 5 per 50HPF). Moreover, immunochemical analysis revealed positivity for c-kit (CD117) and DOG-1. There were no complications 2 months after surgery.

Conclusions

Intussusception associated with GIST is a rare finding that can be life-threatening if it occurs with an ulcer. This case showed that the early detection of bleeding and emergency surgery could prevent severe complications.

A novel technique for removing large gastric subepithelial tumors with ESD method in the subcardia region

Previously, patients with tumors larger than 4 cm in sub-cardia region usually received open gastrectomy. Due to its anatomic features, the cardia is often considered as a contraindicated area for endoscopic resection. Herein, we report a novel technique of endoscopic submucosal dissection (ESD) which facilitates the removal of gastric subepithelial tumors (SMTs) larger than 4 cm in the subcardia and fundus region. This is a retrospective case series of patients with SMTs larger than 4 cm in the subcardia and fundus regions who received the novel procedure of ESD between October 2015 and October 2016. The novel procedure of ESD involved a median linear incision of the mucosa being made in the central area of the tumor, followed by the submucosal dissection. The residual defect was finally closed using titanium endoclips. The endoscopical outcomes, histopathological findings as well as other complications were assessed. Eight patients fulfilled the entry criteria. The mean lesion size was 45.6±7.5 mm (range: 40.0-65.0 mm), and the mean operating time was 83±13 min (range: 60-100 min). The en bloc resection rate was 100%. Although perforations occurred in 5 out of 8 patients, they were successfully closed with endoclips. The median length of inpatient hospital stay was 6 days (range: 5-8 days). No patients needed further gastrectomy. The median follow-up was 36 months and none of the patients developed local recurrence or distant metastasis. The advanced procedure of ESD is feasible and safe for tumors more than 4 cm in the subcardia region. It could be applied as a novel technique for treating patient without surgical interventions.

A Novel Pathological Prognostic Score (PPS) to Identify "Very High-Risk" Patients: a Multicenter Retrospective Analysis of 506 Patients with High Risk Gastrointestinal Stromal Tumor (GIST)

BACKGROUND

To determine the better risk stratification based on surgical pathology and to assess the clinical outcomes after curative resection with a new scoring system in high risk gastrointestinal stromal tumor (GIST) patients.

METHODS

We retrospectively evaluated 506 high-risk GIST patients who underwent curative resection as initial treatment at four centers from 2001 to 2015.

RESULTS

Multivariate analysis revealed that only Ki-67 labeling index (LI) and mitotic index were independent prognostic factors of overall survival (OS). For the two tumor-related pathological factors, Ki-67 LI > 7% and mitotic index ≥ 7/50 high power fields were allocated 1 point each. The total score was defined as the Pathological Prognostic Score (PPS). When Ki-67 LI and mitotic index were replaced by PPS, a multivariate analysis still identified PPS as an independent predictor of OS (HR 2.719; 95% CI 1.309-5.650; P = 0.007). Patients with a PPS of 0, 1, or 2 had a 5-year survival of 91.8, 79.8, and 51.0%, respectively (P = 0.001). Furthermore, an elevated PPS (PPS = 2) was associated with larger tumor size, non-stomach tumor, and open resection (all P < 0.05).

CONCLUSION

The PPS independently predicted postoperative survival in high-risk GIST, and it might facilitate the selection of appropriate treatment strategy for these patients.

Robotic Gastrotomy With Intracorporeal Suture for Patients With Gastric Gastrointestinal Stromal Tumors Located at Cardia and Subcardiac Region

PURPOSE

Few studies of robotic gastric gastrointestinal stromal tumors (GISTs) resection have been conducted. This study was aimed to evaluate the robotic gastrotomy with intracorporeal suture for patients with GISTs located at cardia and subcardiac region.

MATERIALS AND METHODS

From January 2014 to August 2016, 11 patients with GISTs located at cardia and subcardiac region underwent robotic gastrotomy with intracorporeal suture. Data of these patients were collected.

RESULTS

The mean operative time was 82.7 minutes and the mean blood loss was 30.0 mL. No complication was reported. The postoperative length of stay was 3.3 days. On postoperative day 14, inflammation recovered to preoperative level. On postoperative month 6, the nutritional status was similar to that before the surgery. After 25.5 months follow-up, all patients survived with no recurrence or metastasis.

CONCLUSIONS

Robotic gastrotomy with intracorporeal suture for patients with GISTs located at cardia and subcardiac region is safe and feasible.

Imatinib rechallenge in patients with advanced gastrointestinal stromal tumors following progression with imatinib, sunitinib and regorafenib

BACKGROUND

Rechallenge with imatinib is an option in advanced gastrointestinal stromal tumor (GIST) patients following progression with standard tyrosine-kinase inhibitors (TKIs), imatinib, sunitinib and regorafenib. We retrospectively collected data from metastatic Italian GIST patients treated with imatinib resumption after progression to conventional TKIs.

METHODS

A total of 104 eligible advanced GIST patients, previously treated with imatinib, sunitinib and regorafenib, were collected from six referral Italian institutions. Mutational analysis was recorded and correlated with survival and response according to RECIST 1.1 or CHOI criteria.

RESULTS

Overall, 71 patients treated with imatinib 400 mg as rechallenge were included. Mutational status was available in all patients. The median follow up was 13 months. In patients who received a rechallenge therapy, the median time to progression (TTP) was 5.4 months [95% confidence interval (CI) 1.9-13.5] and overall survival (OS) was 10.6 months (95% CI 2.8-26.9). A correlation between mutational status, response rate, TTP and OS was not found but comparing deleted versus nondeleted KIT exon 11 patients, a significant difference was identified in terms of TTP and OS (p = 0.04 and p = 0.02, respectively).

CONCLUSIONS

Our retrospective data confirm that imatinib rechallenge is a reasonable option in advanced GIST. The prognostic value of the specific KIT mutations was confirmed in our series.

Small bowel gastrointestinal stromal tumor: a retrospective study of 32 cases at a single center and review of the literature

Background

Gastrointestinal stromal tumor (GIST) is a rare tumor of the small bowel, which can be difficult to diagnose and has a varied clinical outcome.

Purpose

This is a retrospective review of the diagnosis, management, and clinical outcome of 32 patients diagnosed with primary small bowel GIST from a single center and a comparison of the findings with previously published cases.

Patients and methods

Retrospective review of data from patient clinical records, endoscopic and imaging findings, surgical procedures, tumor histology and immunohistochemistry, and clinical outcome was conducted.

Results

Data of 32 patients with a median age of 56 years including 50% men and women were reviewed. The majority (29/32) were symptomatic at presentation, with the main symptom being gastrointestinal bleeding (15/32). Imaging detection rates included ultrasound (0%), magnetic resonance imaging (0%), computed tomography (54.8%), computed tomography angiography (71.4%), and double-balloon enteroscopy (88.9%). The mean tumor diameter was 5.3 cm; 4 tumors were located in the duodenum, 21 in the jejunum, and 7 in the ileum. Based on the tumor size and mitotic index, 5 (15.6%), 15 (46.9%), 0 (0%), and 12 (37.5%) patients were classified into very low-risk, low-risk, intermediate-risk, and high-risk groups. Immunohistochemistry showed positive expression for CD117 (100%), CD34 (81.2%), DOG1 (93.8%), smooth muscle actin (37.5%), S100 (9.4%), and desmin (6.2%). Twenty-five patients (78.1%) were treated with open surgical tumor resection; seven patients (21.9%) underwent laparoscopic surgery. Postoperative complications that occurred in seven patients (21.9%) were resolved with conservative management. Four patients were treated with postoperative imatinib. At median follow-up of 30 months, two patients were died.

Conclusion

The findings from this case series, combined with the findings from previously published cases, provide an update on the current status of the diagnosis and the therapeutic approaches that might lead to improvement in prognosis for patients who present with primary small bowel GIST.

Asian consensus guidelines for gastrointestinal stromal tumor: what is the same and what is different from global guidelines

There are some disparities between the clinical practice and profiles of cancer in Asia and those in Europe & North America. In Asia, surgical oncologists still have a major role in the multidisciplinary therapy of gastrointestinal stromal tumor (GIST), whereas medical oncologists hold this status in the West. Although the incidence of clinical GIST is considered similar between the two areas, small gastric GISTs are more frequently treated by surgery in East Asia compared with Europe & North America. The diagnosis and treatment of small submucosal tumors (SMTs), including GIST, is important in Asian clinical practice guidelines for GIST. Most items of Asian and Western GIST guidelines are very similar. There are slight differences between the two guidelines in the degree of recommendation, which may come from disparities of clinical practice and available medicines. Importantly, most clinical evidence in the GIST guidelines has been established by clinical trials conducted in Western countries, and the number of clinical trials is still limited in Asia, suggesting that Asian GIST patients may have limited access to investigational drugs after standard therapy. Finally, both Asian and Western GIST guidelines are well-harmonized in some parts, and their contents may reflect the medical circumstances of each region.

Ultrasound-Guided Intraoperative Radiofrequency Ablation and Surgical Resection for Liver Metastasis from Malignant Gastrointestinal Stromal Tumors

Objective

To evaluate the effectiveness, safety, and feasibility of intraoperative radiofrequency ablation (IORFA) under ultrasound guidance for the treatment of liver metastases from gastrointestinal stromal tumors (GISTs).

Materials and Methods

From August 2009 to February 2017, 24 patients with liver metastases of GISTs underwent IORFA, 14 underwent concurrent IORFA and primary GIST resection, and 10 underwent IORFA to treat hepatic recurrence after previous primary GIST resection. Seventy-six hepatic metastases were treated, of which 47 were surgically resected and 29 underwent IORFA. All included patients received imatinib therapy as standard treatment before and after IORFA or surgical resection. A retrospective medical record review was conducted, and follow-up data were collected. Technical success and effectiveness, overall and GIST-specific survival, and complications were assessed.

Results

The mean follow-up duration was 50.7 ± 34.7 months. The technical success rate of IORFA was 100%. New metastases developed in three of the 24 patients (12.5%) following a complete response 16, 51, and 95 months after IORFA, respectively. The cumulative one-, three-, and five-year overall survival rates were 100, 94.4, and 87.7%, respectively. The one-, three-, and five-year GIST-related survival rates were 100, 94.4, and 94.4%, respectively. Two major complications (biliary stricture and hepatic abscess) were observed.

Conclusion

IORFA appears to be a feasible and safe treatment option for liver metastasis in patients with primary GISTs. In addition, IORFA and surgical resection may be complementary, helping to obtain complete response in cases of otherwise inoperable liver metastases secondary to GISTs.

Extra-gastrointestinal stromal tumor of the pancreas: report of a case

Gastrointestinal tumors (GISTs) of the pancreas are extremely rare with limited individual case reports and small number of case series. Herein, we report a case of pancreatic extragastrointestinal stromal tumor (EGIST) along with literature review. A 64-year-old female patient was referred to us for treatment of an abdominal mass detected by ultrasonographic examination. The tumor was located in the periamullary region. Under a preoperative diagnosis of a duodenal GIST, we performed a pylorus preserving pancreatoduodenectomy for this lesion. Laboratory examination results were within normal ranges. On pathologic gross examination, the tumor measured at 7 cm in its greatest dimension almost entirely involved the pancreatic head. Its cut surface was rubbery and white. It was surrounded by a thin pseudocapsule and well demarcated. Histopathological examination of the specimen showed a cellular lesion with compressed pancreatic tissue at peripheral. Mitotic count was 5 per 50 high-power fields. Immunohistochemically, neoplastic cells were positive for antibodies against C-KIT (CD117), CD 34, and vimentin. However, smooth-muscle actin reactions with antibodies against S-100 or desmin were negative. Based on above findings, the tumor was finally diagnosed as GISTs originating from the pancreas. The patient has been followed up postoperatively for 72 months. There is no evidence of recurrence. Here we report this case of pancreatic EGIST presenting as a solid neoplasm along with literature review of cases previously described. Our review on pancreatic EGISTs is limited and insufficient to make a conclusion regarding its clinical features. Those manifested large masses tended to have an aggressive biological and clinical behavior. Thus, pancreatic EGISTs need to be carefully differentiated. Adequate surgical intervention is necessary for pancreatic EGISTs.

Current research and treatment for gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract and have gained considerable research and treatment interest, especially in the last two decades. GISTs are driven by mutations commonly found in the KIT gene and less commonly in the platelet-derived growth factor receptor alpha gene, BRAF gene and succinate dehydrogenase gene. GISTs behave in a spectrum of malignant potential, and both the tumor size and mitotic index are the most commonly used prognostic criteria. Whilst surgical resection can offer the best cure, targeted therapy in the form of tyrosine kinase inhibitors (TKIs) has revolutionized the management options. As the first-line TKI, imatinib offers treatment for advanced and metastatic GISTs, adjuvant therapy in high-risk GISTs and as a neoadjuvant agent to downsize large tumors prior to resection. The emergence of drug resistance has altered some treatment options, including prolonging the first-line TKI from 1 to 3 years, increasing the dose of TKI or switching to second-line TKI. Other newer TKIs, such as sunitinib and regorafenib, may offer some treatment options for imatinib-resistant GISTs. New molecular targeted therapies are being evaluated, such as inhibitors of BRAF, heat shock protein 90, glutamine and mitogen-activated protein kinase signaling, as well as inhibitors of apoptosis proteins antagonist and even immunotherapy. This editorial review summarizes the recent research trials and potential treatment targets that may influence our future patient-specific management of GISTs. The current guidelines in GIST management from Europe, North America and Asia are highlighted.

Laparoscopic techniques and strategies for gastrointestinal GISTs

The laparoscopic approach is widely accepted surgical treatment for gastrointestinal submucosal tumors (SMTs). In this chapter, we will introduce laparoscopic techniques and strategy for gastrointestinal SMTs, in accordance with those for gastrointestinal stromal tumors (GISTs). The indication for a laparoscopic approach has been related to tumor size. The upper limit of tumor size has increased, according to recent trends, and there is no established guideline for a lower limit. All patients undergoing laparoscopic surgery receive preoperative examinations including gastrofiberscopy, upper gastrointestinal radiography, computed tomography (CT), and endoscopic ultrasonography (EUS). Gastric tumors <20 mm in diameter measured by EUS or CT are preoperatively localized by gastrofiberscopic clipping of the mucosa covering the SMT. While maintaining the principle of local resection with a negative resection margin, different surgical techniques are required depending on the location and configuration of the tumor. A single dose of a second-generation cephalosporin is administered to patients as a prophylactic antibiotic before or immediately after operation. If a patient undergoes wedge resection, a semi-bland diet will be provided within 48-72 hours. However, in cases of proximal or distal gastrectomy, the diet will be restricted for several days. A "no-touch" technique, by which the risk of tumor dissemination can be minimized, includes grasping the surrounding tissues, holding the threads sutured at the normal serosa around the tumor, and using a laparoscopic stapler or bag during laparoscopic resection.

Asian Consensus Guidelines for the Diagnosis and Management of Gastrointestinal Stromal Tumor

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors originating in the gastrointestinal tract. With the introduction of molecular-targeted therapy for GISTs which has yielded remarkable outcomes, these tumors have become a model of multidisciplinary oncological treatment. Although Western clinical guidelines are available for GISTs, such as those published by the National Comprehensive Cancer Network (NCCN) and the European Society of Medical Oncology (ESMO), the clinical situations in Asian countries are different from those in Western countries in terms of diagnostic methods, surgical approach, and availability of new targeted agents. Accordingly, we have reviewed current versions of several GIST guidelines published by Asian countries (Japan, Korea, China, and Taiwan) and the NCCN and ESMO and discussed the areas of dissensus. We here present the first version of the Asian GIST consensus guidelines that were prepared through a series of meetings involving multidisciplinary experts in the four countries. These guidelines provide an optimal approach to the diagnosis and management of GIST patients in Asian countries.

Schwannoma of the stomach: a case report

BACKGROUND

Schwannomas, also known as neurilemmomas, are benign slow-growing neoplasms originating from a Schwann cell sheath. These neoplasms are rare among the mesenchymal tumors of the gastrointestinal tract. In the stomach, Schwannomas only represent 0.2 % of all gastric tumors; this makes the presentation of a schwannoma in the stomach of a man in his seventh decade unusual. This case report highlights the rarity of a schwannoma at the greater curvature of the stomach because only a few cases have been reported in the literature. This case describes the importance of including gastric schwannomas in the differential diagnosis when preoperative assessment reveals a submucosal gastric mass with gastrointestinal stromal tumor as a leading differential diagnosis because of its common occurrence at this site.

CASE PRESENTATION

A 72-year-old man of Indian origin presented with a painless abdominal mass with nonspecific gastrointestinal upset. An endoscopy showed a submucosal lesion in his stomach measuring 4 × 3 × 2 cm. Histology revealed a benign spindle cell tumor. Immunohistochemistry confirmed the diagnosis of gastric schwannoma. He is on regular follow-up and doing well.

CONCLUSIONS

It should be remembered that a schwannoma can present as a mass lesion in the stomach and mimic gastrointestinal stromal tumor. Patients should undergo an endoscopy and a biopsy of the lesion should be done. Many patients do not undergo endoscopy which can delay diagnosis and management. As these tumors have an excellent prognosis, surgical removal is sufficient treatment. Surgeons, radiologists, pathologists and gastroenterologists must be aware of this entity.

The standard diagnosis, treatment, and follow-up of gastrointestinal stromal tumors based on guidelines

Although gastrointestinal stromal tumors (GISTs) are a rare type of cancer, they are the commonest sarcoma in the gastrointestinal tract. Molecularly targeted therapy, such as imatinib therapy, has revolutionized the treatment of advanced GIST and facilitates scientific research on GIST. Nevertheless, surgery remains a mainstay of treatment to obtain a permanent cure for GIST even in the era of targeted therapy. Many GIST guidelines have been published to guide the diagnosis and treatment of the disease. We review current versions of GIST guidelines published by the National Comprehensive Cancer Network, by the European Society for Medical Oncology, and in Japan. All clinical practice guidelines for GIST include recommendations based on evidence as well as on expert consensus. Most of the content is very similar, as represented by the following examples: GIST is a heterogeneous disease that may have mutations in KIT, PDGFRA, HRAS, NRAS, BRAF, NF1, or the succinate dehydrogenase complex, and these subsets of tumors have several distinctive features. Although there are some minor differences among the guidelines--for example, in the dose of imatinib recommended for exon 9-mutated GIST or the efficacy of antigen retrieval via immunohistochemistry--their common objectives regarding diagnosis and treatment are not only to improve the diagnosis of GIST and the prognosis of patients but also to control medical costs. This review describes the current standard diagnosis, treatment, and follow-up of GISTs based on the recommendations of several guidelines and expert consensus.

Severe Imatinib-Associated Skin Rash in Gastrointestinal Stromal Tumor Patients: Management and Clinical Implications

PURPOSE

This study evaluated the incidence of imatinib-associated skin rash, the interventional outcomes of severe rash, and impact of severe rash on the outcomes of imatinib treatment in gastrointestinal stromal tumor (GIST) patients.

MATERIALS AND METHODS

A total of 620 patients were administered adjuvant or palliative imatinib for GIST at Asan Medical Center between January 2000 and July 2012. This analysis focused on a group of 42 patients who developed a severe rash requiring major interventions, defined as dose interruption or reduction of imatinib or systemic steroid use.

RESULTS

Of the 620 patients treated with imatinib, 148 patients (23.9%) developed an imatinib-associated skin rash; 42 patients (6.8%) developed a severe rash requiring major intervention. Of these, 28 patients (66.8%) successfully continued imatinib with interventions. Serial blood eosinophil levels during imatinib treatment were associated with skin rash and severity. A significant association was observed between successful intervention and blood eosinophil level at the time of intervention initiation. In metastatic settings, patients with severe rash requiring major interventions tended to show poorer progression-free survival than patients who did not require major intervention and patients with no rash, although this finding was not statistically significant (p=0.326).

CONCLUSION

By aggressive treatment of severe rash through modification of imatinib dose or use of systemic steroid, the majority of patients can continue on imatinib. In particular, imatinib dose intensity can be maintained with use of systemic steroid. Measuring the blood eosinophil levels may be helpful in guiding the management plan for skin rash regarding the intensity and duration of interventions.

Efficacy of Imatinib in Patients with Platelet-Derived Growth Factor Receptor Alpha-Mutated Gastrointestinal Stromal Tumors

Purpose

The incidence of gastrointestinal stromal tumors (GISTs) harboring platelet-derived growth factor receptor alpha (PDGFRA) mutations is low, therefore further investigation of the efficacy of imatinib in this subgroup was needed.

Materials and Methods

Patients with PDGFRA-mutant GISTs who received imatinib as primary therapy for advanced disease between January 2000 and June 2012 were identified from the GIST registry of Asan Medical Center, Seoul, Korea.

Results

KIT and PDGFRA genotyping in 823 patients identified 18 patients (2%) with PDGFRA mutations who were treated with first-line imatinib. Exon 18 D842V substitution, non-D842V exon 18 mutations, and exon 12 mutations were detected in nine (50%), four (22%), and five (28%) patients, respectively. Objective response rate differed significantly between patients with the D842V mutation and those with non-D842V mutations (0% [0/5] vs. 71% [5/7], p=0.03). In all patients, median progression-free survival (PFS) and overall survival (OS) was 24.8 months (95% confidence interval [CI], 0.0 to 57.2) and 51.2 months (95% CI, 37.1 to 65.3), respectively. Significantly, poorer PFS was observed for patients with D842V-mutant GISTs than those with non-D842V PDGFRA-mutant GISTs: median 3.8 months (95% CI, 1.4 to 6.3) versus 29.5 months (95% CI, 18.3 to 40.7) (p < 0.001). Patients with the D842V mutation had poorer OS than those with non-D842V PDGFRA mutations: median 25.2 months (95% CI, 12.7 to 37.8) versus 59.8 months (95% CI, 43.0 to 76.5) (p=0.02).

Conclusion

Imatinib is active against non-D842V PDGFRA-mutant GISTs, whereas GISTs harboring the D842V mutation are primarily resistant to imatinib.

Current endoscopic ultrasound-guided approach to incidental subepithelial lesions: optimal or optional?

Subepithelial lesions (SEL) are identified during endoscopic procedures on a regular basis. They can occur anywhere in the gastrointestinal (GI) tract and are located beneath the normal epithelial layer, which explains why a tissue diagnosis is difficult to obtain with routine biopsies. Endoscopic ultrasound (EUS) is used to further characterize these lesions. EUS can distinguish intramural lesion from extramural compression. Furthermore, it allows allocation of intramural lesions to a specific layer of the GI wall and offers additional information as to whether a lesion could be benign or malignant. EUS also assists in choosing the optimal means of tissue acquisition. The choice of tissue acquisition is based on a number of factors, such as tumor size, EUS features, and location within the GI tract or within a specific layer of the GI wall. Furthermore, local expertise and patient factors should be considered when deciding whether tissue acquisition, surgical intervention or follow up is recommended. In this review we offer an EUS-guided approach to the evaluation of incidental SEL based on current evidence and point out areas of uncertainty, which explain why the proposed algorithmic approach may be optional rather than optimal.

Minimally invasive surgery for submucosal (subepithelial) tumors of the stomach

Minimally invasive surgery has become common in the surgical resection of gastrointestinal submucosal tumors (SMTs). The purpose of this article is to review recent trends in minimally invasive surgery for gastric SMTs. Although laparoscopic resection has been main stream of minimally invasive surgery for gastrointestinal SMTs, recent advances in endoscopic procedures now provide various treatment modalities for gastric SMTs. Moreover, investigators have developed several hybrid techniques that include the advantages of both laparoscopic and endoscopic procedure. In addition, several types of reduced port surgeries, modification of conventional laparoscopic procedures, have been recently applied to the surgical resection of SMTs. Meanwhile, robotic surgery for SMTs requires further evidence and improvement.

The role of surgical resection following imatinib treatment in patients with recurrent or metastatic gastrointestinal stromal tumors: results of propensity score analyses

BACKGROUND

Although benefits of surgical resection of residual gastrointestinal stromal tumors (GISTs) after imatinib therapy have been suggested, those benefits over imatinib alone have not been proven. We compared the clinical outcomes of surgical resection of residual lesions after imatinib treatment (S group) with imatinib treatment alone (NS group) in patients with recurrent or metastatic GISTs.

METHODS

A total of 134 patients (42 in the S group, 92 in the NS group) with recurrent or metastatic GIST who had stable disease for more than 6 months after responding to imatinib were included.

RESULTS

There were no statistically significant differences in the baseline characteristics of the S and NS groups except for age and number of peritoneal metastases. The median follow-up period was 58.9 months. Progression-free survival (PFS) and overall survival (OS) were significantly longer in the S group compared with the NS group (median PFS: 87.7 vs. 42.8 months, p = 0.001; median OS: not reached vs. 88.8 months, p = 0.001). Multivariate analysis revealed that S group, female sex, KIT exon 11 mutations, and low initial tumor burden were associated with longer PFS, and S group and low initial tumor burden were associated with a longer OS. Even after applying inverse probability of treatment weighting adjustment, the S group demonstrated significantly better outcomes in terms of PFS (HR 2.326; 95 % confidence interval [CI] 1.034-5.236; p = 0.0412) and OS (HR 5.464; 95 % CI 1.460-20.408; p = 0.0117).

CONCLUSION

Surgical resection of residual lesions after disease control with imatinib is likely to be beneficial to patients with recurrent or metastatic GISTs.

Resumption of imatinib to control metastatic or unresectable gastrointestinal stromal tumours after failure of imatinib and sunitinib (RIGHT): a randomised, placebo-controlled, phase 3 trial

BACKGROUND

Few treatment options remain for patients with metastatic or unresectable gastrointestinal stromal tumours (GIST) after objective progression on approved tyrosine-kinase inhibitors. We aimed to assess efficacy of imatinib rechallenge in these patients.

METHODS

In our prospective, randomised, double-blind trial, we enrolled adults (≥18 years) who had previously benefited from first-line imatinib (initial response or stable disease for ≥6 months) but whose metastatic or unresectable GIST had progressed on at least imatinib and sunitinib. We randomly allocated participants in a 1:1 ratio, with a centralised computer-generated allocation procedure (random permuted blocks of two, four, and six) and stratified by previous treatment and Eastern Cooperative Oncology Group performance status, to receive best supportive care with imatinib 400 mg per day or matched placebo. Crossover to open-label imatinib was allowed after investigator-adjudicated disease progression. The primary endpoint was progression-free survival (PFS), as determined by a masked external radiological review. All analyses were done for all patients who received at least one dose of study drug.

FINDINGS

Between July 20, 2010, and Jan 17, 2013, we randomly allocated 41 patients to the imatinib group and 40 patients to the placebo group. After a median follow-up of 5·2 months (IQR 3·4-9·4), median PFS was 1·8 months (95% CI 1·7-3·6) with imatinib compared with 0·9 months (0·9-1·7) with placebo (hazard ratio for progression or death 0·46, 95% CI 0·27-0·78; p=0·005). 37 (93%) patients in the placebo group crossed over to open-label imatinib after progression. The most common grade 3 or worse adverse events were anaemia (12 [29%] of 41 patients in the imatinib group vs three [8%] of 40 in the placebo group), fatigue (four [10%] vs none), and hyperbilirubinaemia (three [7%] vs one [3%]).

INTERPRETATION

In patients with GIST that is refractory to treatment with all standard tyrosine-kinase inhibitors, the disease continues to harbour many clones that are sensitive to kinase inhibitors. Continued kinase suppression might slow, although not halt, disease progression.

Phase II study of dovitinib in patients with metastatic and/or unresectable gastrointestinal stromal tumours after failure of imatinib and sunitinib

Background:

This prospective, phase II trial evaluated the efficacy and safety of dovitinib in patients with metastatic and/or unresectable gastrointestinal stromal tumours (GISTs) after failure of at least imatinib and sunitinib.

Methods:

Patients received oral dovitinib, 500 mg once daily, for 5 consecutive days, followed by a 2-day rest, every 28 days. The primary endpoint was disease control rate (DCR; objective response+stable disease (SD)) at 24 weeks, assessed by computed tomography (CT) scan according to RECIST v1.0. Metabolic response was evaluated by positron emission tomography (PET)–CT scans performed at baseline and after 4 weeks of treatment.

Results:

Between September 2011 and April 2012, 30 patients were enroled. DCR at 24 weeks by RECIST v1.0 was 13% and one patient (3%) had a partial response. Based on the European Organization for Research and Treatment of Cancer PET response criteria, four patients (13%) had a metabolic partial response after 4 weeks of treatment. At a median follow-up of 8.3 months (range, 6.3–12.2 months), median progression-free survival (PFS) was 3.6 months (95% confidence interval (CI), 3.5–3.7 months) and median overall survival was 9.7 months (95% CI, 6.0–13.4 months). Metabolic progressive disease at Week 4 was significantly associated with shorter PFS (P=0.03). Grade 3/4 adverse events included asthenia (20%), neutropenia (13%), thrombocytopenia (10%), and hypertriglyceridaemia (10%). Most toxicities were manageable by dose modification.

Conclusion:

Dovitinib showed modest antitumour activity with manageable toxicities in heavily pretreated patients with advanced GISTs.

Surgical treatment of gastric gastrointestinal stromal tumor

Gastrointestinal stromal tumor is the most common mesenchymal tumor in the gastrointestinal tract and is most frequently developed in the stomach in the form of submucosal tumor. The incidence of gastric gastrointestinal stromal tumor is estimated to be as high as 25% of the population when all small and asymptomatic tumors are included. Because gastric gastrointestinal stromal tumor is not completely distinguished from other submucosal tumors, a surgical excisional biopsy is recommended for tumors >2 cm. The surgical principles of gastrointestinal stromal tumor are composed of an R0 resection with a normal mucosa margin, no systemic lymph node dissection, and avoidance of perforation, which results in peritoneal seeding even in cases with otherwise low risk profiles. Laparoscopic surgery has been indicated for gastrointestinal stromal tumors <5 cm, and the indication for laparoscopic surgery is expanded to larger tumors if the above mentioned surgical principles can be maintained. A simple exogastric resection and various transgastric resection techniques are used for gastrointestinal stromal tumors in favorable locations (the fundus, body, greater curvature side). For a lesion at the gastroesophageal junction in the posterior wall of the stomach, enucleation techniques have been tried preserve the organ's function. Those methods have a theoretical risk of seeding a ruptured tumor, but this risk has not been evaluated by well-designed clinical trials. While some clinical trials are still on-going, neoadjuvant imatinib is suggested when marginally unresectable or multiorgan resection is anticipated to reduce the extent of surgery and the chance of incomplete resection, rupture or bleeding.

Clinical practice guidelines for patients with gastrointestinal stromal tumor in Taiwan

For many years, the understanding of gastrointestinal stromal tumors (GISTs), which are the most common mesenchymal tumors of the gastrointestinal tract, has been very limited. However, it is now possible to provide a more precise definition through the use of pathology classification and molecular techniques. Coupled with the advancement of clinical practice, especially the development of targeted therapy, there is now a much better insight into its treatment. At present, organizations such as the National Comprehensive Cancer Network in the USA and the European Society for Medical Oncology in Europe have established a consensus and drawn up guidelines for the diagnosis, treatment, and follow-up of GISTs.With experts coming from various districts in Taiwan and combining the most recent clinical data and experiences, the Taiwan Surgical Society of Gastroenterology drafted the first national GIST treatment guidelines after a consensus meeting in 2007. Following subsequent advances in GIST diagnosis and treatment, further revisions and modifications have been made to the original guidelines. We present here the updated consensus and recommendations of the Taiwan Surgical Society of Gastroenterology for the diagnosis and treatment of GIST. We hope these guidelines can help enhance the quality of diagnosis, treatment, and care of patients with GIST in Taiwan.