NCCN Task Force report: update on the management of patients with gastrointestinal stromal tumors

Submucosal Tunneling Endoscopic Resection

Minimally invasive endoscopic resection procedures continue to evolve, with submucosal tunneling endoscopic resection (STER) being a durable option for en bloc resection of submucosal tumors. Whether STER can be effectively used for larger (>3.5 cm) lesions remains to be seen. STER-ET is a novel approach for removal of extraluminal tumors, but data are currently limited to support its use.

Prevalence, diagnosis, and treatment of primary hepatic gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GIST), which is the most common mesenchymal tumor of the digestive tract, account for 1%-3% of gastrointestinal tumors. Primary stromal tumors outside the gastrointestinal tract are collectively referred to as extra GISTs, and stromal tumors in different regions often have different prognoses. A primary hepatic GIST is a rare tumor with an unknown origin, which may be related to interstitial Cajal-like cells. Although primary hepatic GIST has certain characteristics on imaging, it lacks specific symptoms and signs; thus, the final diagnosis depends on pathological and genetic evidence. This review summarizes all cases of primary hepatic GIST described in the literature and comprehensively analyzes the detailed clinical data of all patients. In terms of treatment, local resection alone or with adjuvant therapy was the prioritized choice to obtain better disease-free survival and longer survival time. For advanced unresectable cases, imatinib mesylate was applied as the first-line chemotherapy agent. Moreover, transcatheter arterial chemoembolization, radiofrequency ablation, and microwave ablation were shown to improve overall survival for selected patients. Liver transplantation was a final treatment option after resistance to chemotherapy developed.

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.

Gastrointestinal Stromal Tumours (GIST): Indian Experience of Rare Malignancy

GISTs are rare tumours of the GI tract arising from the intestinal cells of Cajal. Though various risk stratification systems have been proposed, none has been universally accepted. We audited the survival and recurrence patterns in our patients and evaluated clinicopathological features to identify prognostic factors affecting survival. We conducted a retrospective analysis of patients treated at our hospital from 1999 to 2012. Patient variables, clinicopathological factors and treatment variables were collected. Sixty-three patients were evaluated and treated at our institute of which 38 were non-metastatic. The most common site of origin was the stomach. On univariate analysis, presence of metastasis, male gender, high mitotic rate, non-gastric primary and epithelioid histology were significantly associated with poor overall survival. Tumour size > 10 cm, mitotic rate > 10/50 hpf and presence of necrosis significantly affected disease-free survival for non-metastatic patients. Multivariate analysis showed higher mitotic rate and non-gastric primary to correlate with worse outcome. In our experience, a high mitotic rate and non-gastric primary independently predicted a poor prognosis in GIST.

Asymptomatic large duodenal GIST - An incidental finding in abdominopelvic ultrasonography: A case report

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Duodenal GISTs are rare tumors of the digestive tract and although frequently symptomatic, they can also be diagnosed incidentally.

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The management of GISTs should be conducted by a multidisciplinary team.

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Surgery is the only potentially curative treatment for non-metastatic GISTs and the gold standard for local disease.

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The recurrence of GISTs appears to have a stronger connection to the tumor biology rather than the kind of surgery performed.

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High-risk GISTs have a formal indication for adjuvant therapy with a tyrosine kinase inhibitor.

Introduction

Duodenal GISTs are rare mesenchymal tumors of the digestive tract. They usually present as gastrointestinal bleeding or non-specific abdominal pain, but they can also be asymptomatic. High-risk GISTs have malignant potential. Surgical resection is the only curative option and its extension depends on different factors. Tyrosine kinase inhibitors are of the utmost importance in high-risk and metastatic disease.

Case description

We herein report the case of a 75-year-old male, referred to our general surgery outpatient clinic, with an asymptomatic duodenal mass incidentally diagnosed during an abdominopelvic ultrasonography. Abdominal CT suggested GIST. Since no other lesions were found, a segmental duodenectomy was performed and the patient recovery was uneventful. Histologic exam confirmed the presence of a high-risk GIST, therefore adjuvant therapy with imatinib was initiated.

Discussion

Duodenal involvement by GISTs is rare, even more in its third/fourth portions. The widespread clinical use of radiological exams such as ultrasonography may lead to the diagnosis of asymptomatic masses. Surgical treatment is the gold-standard giving the malignant potential of these neoplasms. There are risk stratification scores that may be used to assess the need for adjuvant therapy.

Conclusion

Even large GISTs can by asymptomatic. Giving their malignant potential, early diagnosis and treatment are crucial. The histologic findings and genetic profile have an impact on the patient’s survival.

Application of A Convolutional Neural Network in The Diagnosis of Gastric Mesenchymal Tumors on Endoscopic Ultrasonography Images

Background and Aims: Endoscopic ultrasonography (EUS) is a useful diagnostic modality for evaluating gastric mesenchymal tumors; however, differentiating gastrointestinal stromal tumors (GISTs) from benign mesenchymal tumors such as leiomyomas and schwannomas remains challenging. For this reason, we developed a convolutional neural network computer-aided diagnosis (CNN-CAD) system that can analyze gastric mesenchymal tumors on EUS images. Methods: A total of 905 EUS images of gastric mesenchymal tumors (pathologically confirmed GIST, leiomyoma, and schwannoma) were used as a training dataset. Validation was performed using 212 EUS images of gastric mesenchymal tumors. This test dataset was interpreted by three experienced and three junior endoscopists. Results: The sensitivity, specificity, and accuracy of the CNN-CAD system for differentiating GISTs from non-GIST tumors were 83.0%, 75.5%, and 79.2%, respectively. Its diagnostic specificity and accuracy were significantly higher than those of two experienced and one junior endoscopists. In the further sequential analysis to differentiate leiomyoma from schwannoma in non-GIST tumors, the final diagnostic accuracy of the CNN-CAD system was 75.5%, which was significantly higher than that of two experienced and one junior endoscopists. Conclusions: Our CNN-CAD system showed high accuracy in diagnosing gastric mesenchymal tumors on EUS images. It may complement the current clinical practices in the EUS diagnosis of gastric mesenchymal tumors.

Development and validation of a prognostic nomogram to predict recurrence in high-risk gastrointestinal stromal tumour: A retrospective analysis of two independent cohorts

BACKGROUND

The risk of recurrence in localised, primary gastrointestinal stromal tumour (GIST) classified as high-risk after complete resection varies significantly. Thus, we aimed to develop a nomogram to predict the recurrence of high-risk GIST after surgery to aid patient selection.

METHODS

We retrospectively evaluated patients (n = 424) with high-risk GIST who underwent curative resection as the initial treatment at two high-volume medical centres, between January 2005 and September 2019. The least absolute shrinkage and selection operator (LASSO) regression model was utilised to select potentially relevant features. Multivariate Cox proportional hazards analysis was used to develop a novel nomogram.

FINDINGS

The nomogram comprised age, fibrinogen levels, prognostic nutritional index (PNI), platelet-lymphocyte ratio (PLR), mitotic counts and tumour size, which provided favourable calibration and discrimination in the training dataset with an AUC of 0•749 and a C-index of 0•742 (95%CI:0•689-0•804). Further, it showed acceptable discrimination in the validation cohort, with an AUC of 0•778 and C-index of 0•735 (95%CI:0•634-0•846). The time-dependant receiver operating characteristic (ROC) curves performed well throughout the observation period. Additionally, the nomogram could classify high-risk GISTs into 'very high-risk' and 'general high-risk' groups with a hazard ratio (HR) of 5•190 (95%CI: 3•202-8•414) and 5•438 (95%CI: 2•236-13•229) for the training and validation datasets, respectively.

INTERPRETATION

The nomogram independently predicted post-operative recurrence-free survival (RFS) in high-risk GIST and showed favourable discrimination and calibration values. It may be a useful clinical tool for identifying 'very high-risk' GIST, by allowing treatment strategy optimisation in these patients.

FUNDING

National Natural Science Foundation of China (No. 81702386 and 81874184).

Is nonanatomic rectal resection a valid therapeutic option for rectal gastrointestinal stromal tumors? A proposed decision algorithm

BACKGROUND AND OBJECTIVES

The best surgical approach to rectal gastrointestinal stromal tumors (GISTs) is still debated, and both nonanatomic rectal resection (NARR) and anatomic rectal resection (ARR) are applied. The aim of this study was to evaluate the feasibility and oncological outcomes of NARR and ARR for rectal GISTs (R-GISTs).

METHODS

Through a large French multicentre retrospective study, 35 patients were treated for R-GIST between 2001 and 2013. Patients who underwent NARR and ARR were compared.

RESULTS

There were 23 (65.7%) patients in group ARR and 12 (34.3%) in group NARR. Significantly more patients in the group with ARR had a neoadjuvant treatment (86%) with tyrosine kinase inhibitor (TKI) (imatinib) compared to those with NARR (25%) (p < .01). The median preoperative tumor size was significantly different between the groups without and with neoadjuvant TKI: 30 ± 23 mm versus 64 ± 44.4 mm, respectively (p < .001). Overall postoperative morbidity was 20% (n = 7) (26% for ARR vs. 8% for NARR; p = .4). After a median follow-up of 60.2 (3.2-164.3) months, the 5-year disease-free survival rates were 79.5% (confidence interval [CI] 95%: 54-100) for the NARR group and 68% (CI 95%: 46.4-89.7) for the ARR group (p = .697), respectively.

CONCLUSION

The use of NARR for small R-GIST's does not seem to impair the oncological prognosis.

Factors Associated with Operation Time of Laparoscopic Gastric Wedge Resection for Gastric Subepithelial Tumors

Purpose

Gastric subepithelial tumor (GST) is a disease entity that includes all gastric subepithelial lesions. The oncologically safe surgical technique is complete resection with adequate resection margins. Most of the studies about laparoscopic gastric wedge rsection (LGWR) in GST focus on oncologic curability or surgical effectiveness. However, studies on the factors associated with the operation time are rare. Therefore, this study was conducted to analyze and compare the factors associated with the operation time of LGWR.

Methods

From 2010 to 2019, 145 consecutive patients undergoing LGWR were reviewed retrospectively. Clinical characteristics of GST and operation time were analyzed and compared.

Results

A total of 145 patients was enrolled and reviewed. There were 59 males (40.7%) and 86 females (59.3%) with a mean age of 53.6 years and mean body mass index (BMI) of 23.9 kg/m2. Mean tumor size was 2.9 cm and mean operation time was 66.0 minutes. In statistically, the mean operation time showed significant association with tumor size, BMI, longitudinal tumor location and tumor location between lesser and greater curvature. In multivariate analysis, tumor size, BMI and longitudinal classification of tumor location are statistically significant.

Conclusion

A shorter operation time is expected when there is a small tumor, low BMI and mid portion of the stomach GST. Preoperative evaluation for tumor size and body weight is important. In patients with large GST, obesity and both end stomach GST, we think that pre-operative preparation for long operation time should be considered.

A Novel Snare Traction-Assisted Method During Endoscopic Resection for Upper Gastrointestinal Submucosal Tumors

Background: Traction-assisted endoscopic resection is an approach to provide better procedural outcomes than conventional endoscopic procedure in treating gastric or esophageal epithelial lesions. Submucosal tumors (SMTs) are challenging to resect endoscopically due to the difficulty in exposure and high incidence of full-thickness resection. In this study, we investigated the efficacy of snare traction-assisted method, served as an "extra hand," for upper gastrointestinal SMTs. Methods: From June 2019 to May 2020, we used the snare traction-assisted method to treat 11 patients with 12 upper gastrointestinal SMTs in the Sixth Affiliated Hospital, Sun Yat-sen University. The duration of the procedures and the outcomes were recorded. Results: A total of 11 patients with 12 lesions were treated by snare traction-assisted endoscopic resection. The mean procedure time was 26.8 ± 8.3 minutes. En bloc resection was achieved in all the 12 lesions. The mean length of the specimens was 11.5 ± 4.0 mm. Full-thickness resection was performed in four lesions. The patients were discharged in 5.0 days after procedures without delayed bleeding or other complication reported. Conclusion: Snare traction-assisted method is an effective tool for endoscopic resection of upper gastrointestinal SMTs. Further prospective studies comparing the snare traction-assisted method with the conventional procedure are necessary.

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.

Spectrum of activity of dasatinib against mutant KIT kinases associated with drug-sensitive and drug-resistant gastrointestinal stromal tumors

BACKGROUND

The majority of GISTs express mutationally activated KIT. Imatinib and sunitinib are approved KIT-inhibiting therapies. Their efficacy is usually hampered by the acquired multiple secondary drug-resistance KIT mutations. The most problematic resistance subset is GISTs with acquisition of secondary mutations in the KIT activation loop. Here, we establish the spectrum of activity of dasatinib against a comprehensive collection of clinically relevant KIT mutants associated with drug-sensitive and drug-resistant GIST.

METHODS

The cellular and in vitro activities of tyrosine kinase inhibitors (TKIs) against mutant KIT were assessed using a panel of engineered and GIST-derived cell lines. The in vivo activities of dasatinib were determined using TKI-resistant xenograft models.

RESULTS

In engineered and GIST-derived cell lines, dasatinib potently inhibited KIT with primary mutations in exon 11 or 9 and a range of secondary imatinib-resistant mutations in exons 13 and 14, encoding the ATP-binding pocket, and in exons 17 and 18, encoding the activation loop, with the exception of a substitution at codon T670. Our data show that dasatinib is more potent than imatinib or sunitinib at inhibiting the activity of drug-resistant KIT mutants. Dasatinib also induces regression in GIST-derived xenograft models containing these secondary mutations. A major determinant of the efficacy of dasatinib for the treatment of advanced GIST is the activity of this inhibitor against KIT mutants.

CONCLUSION

Dasatinib shows efficacy in cancer models, inhibiting a wide range of oncogenic primary and drug-resistant KIT mutants. These results have implications for the further development of dasatinib precision therapy in GIST patients.

Primary mesenteric gastrointestinal stromal tumor presented with acute small bowel obstruction

Primary mesenteric gastrointestinal stromal tumors may give rise to abdominal emergencies like bowel obstruction and should be considered in the differential diagnosis to reduce morbidity and mortality. The present study presents an unusual case of primary mesenteric gastrointestinal stromal tumor presenting with small bowel obstruction. A 44-year-old healthy male presented with abdominal pain for 2 days. Detailed examination revealed presence of a 4 × 4 cm mass in the small bowel mesentery with multiple small bowel loops adherent to it, together with their mesentery. The patient was diagnosed with primary gastrointestinal stromal tumor of the small bowel mesentery. He had an uneventful postoperative course and was discharged on the second postoperative day in a good condition. The case analysis showed that the diagnosis of gastrointestinal stromal tumor is likely with the emergence of CD117, despite of its occurrence at rare sites and it is a vague clinical picture.

Do microscopic surgical margins matter for primary gastric gastrointestinal stromal tumor?

BACKGROUND

Although tumor size and mitotic rate are established prognostic factors for worse survival in patients undergoing surgical resection for gastric gastrointestinal stromal tumors, the impact of microscopic margins, or R1 resection, is not completely established.

METHODS

Patients who received no neoadjuvant therapy and underwent surgical resection for stage I to III gastric gastrointestinal stromal tumors were identified from the 2010 to 2013 National Cancer Database and divided into 2 cohorts, R0 and R1 resections. Cox proportional hazards ratio and Kaplan Meier survival estimates were utilized to analyze 5-y overall survival.

RESULTS

Of 2,084 patients, those with R1 resection (57, 2.7%) were more likely to have tumors >10 cm (28.1% vs 11.9%, odds ratio 3.51, P = .017) and stage III disease (26.3% vs 11.2%, odds ratio 2.26, P = .047). Although margin status was associated with higher risk tumors, it was not associated with receipt of adjuvant therapy. After multivariate Cox regression, R1 and R0 patients did not have a difference in 5-y overall survival (82.5% vs 88.6%, hazards ratio 1.26, P = .49). When stratified by stage of disease, there remained no difference in survival across all stages when comparing R1 and R0 patients.

CONCLUSION

Positive microscopic margins are uncommon but do not appear to impact survival outcomes in patients with resected localized gastric gastrointestinal stromal tumors.

Peroral endoscopic tumor resection (POET) with preserved mucosa technique for management of upper gastrointestinal tract subepithelial tumors

BACKGROUND

Third space endoscopy technique facilitates therapeutic endoscopy in subepithelial space. This study aimed to investigate peroral endoscopic tumor resection (POET) with preserved mucosa technique for upper gastrointestinal tract subepithelial tumors (UGI-SETs) removal.

METHODS

Between February 2011 and December 2019, consecutive patients with SETs of esophagus and stomach who underwent POET for enlarging size during follow-up, malignant endoscopic ultrasound features or by patient's request were enrolled. Demographic, endoscopic and pathological data were analyzed retrospectively.

RESULTS

Totally 18 esophageal (mean ± SD age, 55.23 ± 4.15 year-old, 38.89% female) and 30 gastric (52.65 ± 2.43 year-old, 53.33% female) SETs in 47 patients (one with both esophageal and gastric lesions) were resected. The mean (± SD) endoscopic/pathological tumor size, procedure time, en-bloc/complete resection rate, and hospital stays of esophageal and gastric SET patients were 12.36 (± 7.89)/11.86 (± 5.67) and 12.57 (± 6.25)/12.35 (± 5.73) mm, 14.86 (± 6.15) and 38.21 (± 15.29) minutes, 88.89%/94.44% and 86.77%/93.30%, and 4.14 (± 0.21) and 4.17 (± 0.20) days, respectively. The overall complication rate was 18.75%, including 6 self-limited fever and 3 pneumoperitoneum relieved by needle puncture. There was no mortality or recurrence reported with mean follow-up period of 23.74 (± 4.12) months.

CONCLUSIONS

POET is a safe and efficient third space endoscopic resection technique for removal of UGI-SETs less than 20 mm. Long term data are warranted to validate these results.

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.

Surgical options for submucosal tumors near the esophagogastric junction: does size or location matter?

Background

Submucosal tumors (SMTs) of different etiologies exist from esophagus to rectum. Esophagogastric junction (EGJ) is one of the known difficult locations for tumor resection. Although minimally invasive surgery (MIS) is a well-established approach for gastrointestinal surgery, there is no consensus that MIS for resection of SMTs around EGJ is superior to laparotomy. We tried to clarify the factors that determine the surgeons’ choices between these two approaches.

Methods

From January 2002 to June 2016, 909 patients with SMTs underwent resection in our department. Among them, 119 patients (13%) had SMTs around EGJ were enrolled by retrospective review. The clinicopathological features and tumor-related parameters were reviewed and analyzed.

Results

The cohort was stratified into three groups according to the extent of gastrectomy and surgical approaches. The three groups are as following: major gastrectomy (n = 13), minor gastrectomy by laparotomy (n = 51), and minor gastrectomy with MIS (n = 55). The average tumor size was significantly larger in the major gastrectomy group than in the two minor gastrectomy groups; however, there was no difference between the two minor gastrectomy groups (5.33 cm, 4.07 cm, and 3.69 cm, respectively). The minor gastrectomy with MIS required least hospital stay and operation duration also. We re-stratify the two minor gastrectomy groups (n = 106) according to the orientation of SMTs around the EGJ into 4 zones. Most of SMTs located on the greater curvature side of the EGJ were resected with MIS (82% versus 18%), whereas SMTs in the other zones were resected more often by laparotomy (59% versus 41%). There was no surgical mortality within the cohort, while minor gastrectomy with MIS yielded least number of leakages among the three groups.

Conclusions

For SMTs around the EGJ, larger tumors (diameter of more than 5 cm) are more likely to be resected with major gastrectomy. To resect SMTs around the EGJ in a wedge-like (minor gastrectomy) fashion, tumors located other than the greater curvature side were more often resected by laparotomy. However, MIS yielded acceptable safety and surgical outcomes compared to conventional laparotomy for SMTs around the EGJ of the same size.

Laparoscopic Versus Open Surgery for Gastric Gastrointestinal Stromal Tumors: a Propensity Score Matching Analysis

BACKGROUND

Surgery is the first choice for the treatment of gastric gastrointestinal stromal tumors (GISTs). With the development of new instruments and techniques, the popularity of laparoscopic resection of GISTs has increased rapidly. Previous studies on the advantages of laparoscopic resection over open surgery are generally limited by methodology or data capacity. This study evaluated the efficacy of laparoscopic resection and open surgery in gastric GISTs using the propensity score matching (PSM) method.

METHODS

Between January 2005 and December 2017, 1027 patients were diagnosed with primary GIST at our institution. Among them, 548 patients were enrolled in this study. Standard demographic and clinicopathological data were collected from our database. Selection bias was eliminated using the PSM methods.

RESULTS

After PSM, 256 cases involved in the comparison (128 laparoscopic (LAP) vs. 128 open surgery (OPEN)) were randomly matched (1:1) by age, sex, body mass index, hypertension, diabetes, heart disease, year of surgery, tumor location, tumor size, mitotic rate, and treatment with adjuvant tyrosine kinase inhibitors. The LAP group was superior to the OPEN group in blood loss (χ² = 6.048, P = 0.049), time to first flatus (49.41 ± 7.56 vs. 71.31 ± 4.87 h, P < 0.001), and hospital stay (10.21 ± 6.05 vs. 12.56 ± 5.43 days, P = 0.001). No significant differences were seen in either the relapse-free survival or overall survival between the LAP and OPEN groups. In tumors located in favorable locations, the LAP group showed less blood loss (P = 0.008) and less multivisceral resection (17.8% vs. 5.5%, P = 0.02).

CONCLUSIONS

Laparoscopic resection for gastric GISTs is associated with improved surgical outcomes and postoperative courses and comparable oncological outcomes, regardless of favorable or unfavorable tumor location.

The prognostic value of gender in gastric gastrointestinal stromal tumors: a propensity score matching analysis

Background

Gastrointestinal stromal tumors (GISTs) of the stomach are the most common GISTs. The risk, incidence, and outcome of cancer are different between the sexes. Whether gender is related to the prognosis of gastric stromal tumors is unclear. Therefore, this study aims to explore the relationship between gender and gastric GIST prognosis.

Methods

Data from gastric GIST patients were collected from the Surveillance, Epidemiology, and End Results (SEER) database. Propensity score matching (PSM) was performed to reduce confounding factors, and the clinicopathological features and prognosis of GIST patients were comprehensively evaluated.

Results

There were 512 male patients and 538 female patients with gastric GIST. The gender of gastric GIST patients was associated with marital status, surgical treatment, tumor size, and mitotic index (P < 0.05). The Kaplan-Meier analysis and log-rank test revealed that male patients had a higher mortality rate than female patients (P = 0.0024). After matching all the potential confounding factors, the survival of the female gastric GIST patients was better than that of the male gastric GIST patients (P = 0.042). Cox regression analysis revealed that gender was an independent risk factor for overall survival. The risk of death was higher for males than for females (HR 1.677, 95% CI 1.150–2.444, P = 0.007).

Conclusion

Gender could be a prognostic factor for gastric GIST survival, and male patients had a higher risk of death.

EUS-guided fine-needle biopsy sampling versus FNA in the diagnosis of subepithelial lesions: a large multicenter study

BACKGROUND AND AIMS

Although conventional EUS-guided FNA (EUS-FNA) has previously been considered first-line for sampling subepithelial lesions (SELs), variable accuracy has resulted in increased use of fine-needle biopsy (FNB) sampling to improve diagnostic yield. The primary aim of this study was to compare FNA versus FNB sampling for the diagnosis of SELs.

METHODS

This was a multicenter, retrospective study to evaluate the outcomes of EUS-FNA and EUS-guided FNB sampling (EUS-FNB) of SELs over a 3-year period. Demographics, lesion characteristics, sensitivity, specificity, accuracy, number of needle passes, diagnostic adequacy of rapid on-site evaluation (ROSE), cell block accuracy, and adverse events were analyzed. Subgroup analyses were performed comparing FNA versus FNB sampling by location and diagnostic yield with or without ROSE. Multivariable logistic regression was also performed.

RESULTS

Two hundred twenty-nine patients with SELs (115 FNA and 114 FNB sampling) underwent EUS-guided sampling. Mean patient age was 60.86 ± 12.84 years. Most lesions were gastric in location (75.55%) and from the fourth layer (71.18%). Cell block for FNB sampling required fewer passes to achieve conclusive diagnosis (2.94 ± 1.09 vs 3.55 ± 1.55; P = .003). The number of passes was not different for ROSE adequacy (P = .167). Immunohistochemistry was more able to be successfully performed in more FNB sampling samples (69.30% vs 40.00%; P < .001). Overall, sensitivity and accuracy were superior for FNB sampling versus FNA (79.41% vs 51.92% [P = .001] and 88.03% vs 77.19% [P = .030], respectively). On subgroup analysis, sensitivity and accuracy of FNB sampling alone was superior to FNA + ROSE (79.03% vs 46.67% [P = .001] and 87.25% vs 68.00% [P = .024], respectively). There was no significant difference in diagnostic yield of FNB sampling alone versus FNB sampling + ROSE (P > .05). Multivariate analysis showed no predictors associated with accuracy. One minor adverse event was reported in the FNA group.

CONCLUSIONS

EUS-FNB was superior to EUS-FNA in the diagnosis of SELs. EUS-FNB was also superior to EUS-FNA alone and EUS-FNA + ROSE. These results suggest EUS-FNB should be considered a first-line modality and may suggest a reduced role for ROSE in the diagnosis of SELs. However, a large randomized controlled trial is required to confirm our findings.

Diagnosing Gastric Mesenchymal Tumors by Digital Endoscopic Ultrasonography Image Analysis

Gastric mesenchymal tumors (GMTs) are incidentally discovered in national gastric screening programs in Korea. Endoscopic ultrasonography (EUS) is the most useful diagnostic modality for evaluating GMTs. The differentiation of gastrointestinal stromal tumors from benign mesenchymal tumors, such as schwannomas or leiomyomas, is important to ensure appropriate clinical management. However, this is difficult and operator dependent because of the subjective interpretation of EUS images. Digital image analysis computes the distribution and spatial variation of pixels using texture analysis to extract useful data, enabling the objective analysis of EUS images and decreasing interobserver and intraobserver agreement in EUS image interpretation. This review aimed to summarize the usefulness and future of digital EUS image analysis for GMTs based on published reports and our experience.

Gastrointestinal Stromal Tumors: A Single Institution Experience of 176 Surgical Patients

Large single-institution series of patients undergoing resection for gastrointestinal stromal tumors (GIST) are lacking. Clinicopathologic characteristics and postoperative outcomes were retrospectively collected and analyzed from patients undergoing resection for GIST from 2002 to 2011. One hundred seventy-six patients were identified; 156 underwent resection of primary nonmetastatic disease. KIT mutations were identified in 131 patients (84.0%). Of the 156 patients with primary disease, the most common site was the stomach (75.6%). Tumors were categorized as very low (24.4%), low (35.9%), intermediate (12.2%), high (24.4%), or unknown (3.2%) risk. Symptomatic patients more often had high risk (35.6 vs 9.8%; P < 0.0001) and larger tumors (7.3 vs 3.0 cm; P < 0.0001). Forty-seven patients (30.1%) underwent laparoscopic resection (LR). Compared with open surgery, LR was performed for smaller tumors (3.8 vs 6.2 cm; P = 0.002). Positive margin rates were similar (4.3% LR vs 10.2% open; P = 0.346). Median follow-up for the 156 patients with primary tumors was 32.9 months; mean overall survival was 120.9 months (median not reached). Of the 20 patients with metastatic GIST (excluded from above analysis), five patients (25.0%) died of disease with a median follow-up of 15.9 months. Most patients with resectable primary GIST have a favorable prognosis. The presence of symptoms directly related to GIST may be associated with a poor prognosis and is likely related to increased tumor size. Laparoscopic resection is well tolerated and does not appear to compromise outcomes in well-selected patients. Highly selected patients with metastatic disease may benefit from resection.

Reliability of Endoscopic Ultrasound Using Miniprobes and Grayscale Histogram Analysis in Diagnosing Upper Gastrointestinal Subepithelial Lesions

Background

To assess the role of endoscopic ultrasound (EUS) in the diagnosis of upper gastrointestinal subepithelial lesions (SELs) and to investigate EUS combined with a grayscale histogram analysis for the differentiation of leiomyomas and gastrointestinal stromal tumors (GISTs).

Methods

A retrospective study of 709 patients with upper gastrointestinal SELs was conducted by EUS before endoscopic resection. The EUS findings of SELs and pathological results after endoscopic resection were compared. The EUS images of SELs, particularly, leiomyoma and GIST, were further analyzed via a grayscale histogram to differentiate between the two tumors.

Results

Of the 709 patients, 47 cases were pathologically undetermined. The diagnostic consistency of EUS with endoscopic resection was 88.2% (584/662), including 185 muscularis mucosa, 61 submucosa, and 338 muscularis propria, respectively. The diagnostic consistency of EUS with pathology was 80.1% (530/662). The gray value of GISTs was significantly higher than that of leiomyomas (58.9 ± 8.3 vs. 39.5 ± 5.9, t = 57.0, P < 0.0001). The standard deviation of leiomyomas was significantly lower than that of GISTs (20.6 ± 7.0 vs. 39.8 ± 9.3, t = 23.7, P < 0.0001). The grayscale histogram analysis of GISTs showed higher echo ultrasound, and the echo of leiomyoma was more uniform.

Conclusion

EUS is the preferred procedure for the evaluation of upper gastrointestinal SELs. EUS combined with a grayscale histogram analysis is an effective method for the differentiation of leiomyomas and GISTs.

Gastrointestinal Stromal Tumors of the Small Intestine: Progress in Diagnosis and Treatment Research

In recent years, the diagnosis and treatment of gastrointestinal stromal tumors (GISTs) of the small intestine have been a hot topic due to their rarity and non-specific clinical manifestations. With the development of gene and imaging technology, surgery, and molecular targeted drugs, the diagnosis and treatment of GISTs have achieved great success. For a long time, radical resection was prioritized to treat GISTs of the small intestine. At present, preoperative tumor staging is a novel treatment for unresectable malignant tumors. In addition, karyokinesis exponent is the sole independent predictor of progression-free survival of GISTs. The DNA, miRNA, and protein of exosomes have also been found to be biomarkers with prognostic implications. The research on the treatment of GISTs has become a focus in the era of precision medicine, ushering in the use of standardized, normalized, and individualized treatment.

Clinicopathologic and Surgical Characteristics Study of 151 Cases of GIST

BACKGROUND

Gastrointestinal stromal tumor (GIST) is the most appearing mesenchymal tumor of the gastrointestinal system. In this study, we are aiming to share the most up to date knowledge about diagnosis and treatment of these tumors by transferring our clinical experience about GISTs.

METHODS

The 151 patients who were operated between 2006-2020 and whose pathological examination was reported as GIST were analyzed retrospectively. Demographic, clinical, and pathological features and treatment methods of patients were evaluated.

RESULTS

Seeventy-six of the patients were women and 75 of them were men whose age averages were 66.1 (31-86). The most common location was the stomach (55.6%), followed by the small intestine, retroperitoneal, large intestine, rectum, esophagus, and another organ. With surgical intervention, 139 of them had been cured. Twelve of cases were accepted as inoperable. The diameter of tumors in our cases were between 0.4 cm and 35 cm. Determined mitotic activity was ≤ 5 in 71 patients and 5 < in 80 patients. In 8 of 12 unresectable cases, it has been seen that partial remission after the treatment of 12-month tyrosine kinase inhibitors, C-KIT, was positive in 96.7% of our cases. CD34 and Ki-67 was analyzed in patients. CD34 was found positive in 98 (64.9%) of them, Ki-67 was positive in 82 (54.3%) patients. Patients had been observed for 40 months.

CONCLUSION

Despite GISTs are not appearing frequently, nowadays they have started to be seen more frequently than before with the growing present-day diagnostic methods. The ideal treatment is performing radical resection without leaving any tumor cells behind. Tyrosine kinase inhibitors have an important place in unresectable cases.

Small Bowel Gastrointestinal Stromal Tumor as a Gateway for Streptococcus anginosus Causing Multiple Liver Abscesses

Gastrointestinal stromal tumors (GISTs) are the most common type of mesenchymal neoplasm of the gastrointestinal tract but consist of only 1% of all primary gastrointestinal neoplasms. Differentiated from other spindle cell tumors, GISTs are uniquely positive for CD117 expression which allows for molecular targeting therapy with imatinib mesylate (Gleevec). Clinical presentations are variable, ranging from asymptomatic to vague symptoms of abdominal pain, early satiety, abdominal distention or gastrointestinal bleeding. Very rarely, patients can present with tumor-bowel fistula and intra-abdominal abscesses. In this article, we discuss a rare presentation of a middle-aged male with multiple liver abscesses found to have a primary small bowel GIST. This patient received prompt intravenous antibiotics; however, hepatic abscesses can be easily misinterpreted as cystic hepatic metastases which can delay appropriate therapy. Streptococcus anginosus was found to be responsible for the formation of the liver abscesses visualized on computed tomography (CT) scan. Similar to Streptococcus bovis, knowledge in the literature is arising about the association between S. anginosus and gastrointestinal malignancies. This case highlights the importance of identifying concomitant primary GISTs with intra-hepatic abscesses, as these lesions can be easily misconstrued as liver metastases and consequently mismanaged. We herein emphasize that hepatic abscesses are a potential sequela of GISTs and should thus prompt further investigation for potential malignancies, if warranted, so that there is no delay in treatment of these gastrointestinal tumors.

Preclinical Activity of PI3K Inhibitor Copanlisib in Gastrointestinal Stromal Tumor

KIT or PDGFRA gain-of-function mutations are the primary drivers of gastrointestinal stromal tumor (GIST) growth and progression throughout the disease course. The PI3K/mTOR pathway is critically involved in the transduction of KIT/PDGFRA oncogenic signaling regardless of the type of primary and secondary mutations, and therefore emerges as a relevant targetable node in GIST biology. We evaluated in GIST preclinical models the antitumor activity of copanlisib, a novel pan-class-I PI3K inhibitor with predominant activity against p110α and p110δ isoforms, as single-agent and in combination with first-line KIT inhibitor imatinib. In vitro studies undertaken in one imatinib-sensitive (GIST-T1) and two imatinib-resistant (GIST-T1/670 and GIST430/654) GIST cell models showed that single-agent copanlisib effectively suppressed PI3K pathway activation leading to decreased cell viability and proliferation in both imatinib-sensitive and -resistant cells irrespective of the type of primary or secondary KIT mutations. Simultaneous PI3K and KIT inhibition with copanlisib and imatinib resulted in enhanced impairment of cell viability in both imatinib-sensitive and -resistant GIST cell models, although apoptosis was mostly triggered in GIST-T1. Single-agent copanlisib inhibited GIST growth in vivo, and conjoined inhibition of PI3K and KIT was the most active therapeutic intervention in imatinib-sensitive GIST-T1 xenografts. IHC stain for cleaved-caspase 3 and phospho-S6 support a predominant antiproliferative effect of copanlisib in GIST. In conclusion, copanlisib has single-agent antitumor activity in GIST regardless KIT mutational status or sensitivity to imatinib. Effective KIT inhibition is necessary to achieve synergistic or additive effects with the combination of imatinib and any given PI3K/mTOR pathway inhibition.

Clinical course of suspected small gastrointestinal stromal tumors in the stomach

BACKGROUND

Gastric subepithelial lesions are frequently encountered during endoscopic examinations, and the majority of them are small and asymptomatic. Among these lesions, gastrointestinal stromal tumors (GISTs) are the major concern for patients and clinicians owing to their malignant potentials. Although previous guidelines suggested periodic surveillance for such small (≤ 20 mm) lesions, several patients and clinicians have still requested or prescribed repeated examinations or radical resection, posing extra medical burdens and risks.

AIM

To describe the clinical course of suspected small gastric GISTs and provide further evidence for surveillance strategy for tumor therapy.

METHODS

This single-center, retrospective study was conducted at West China Hospital, Sichuan University. Consecutive patients with suspected small gastric GISTs were reviewed from November 2004 to November 2018. GIST was suspected according to endoscopic ultrasonography features: hypoechoic lesions from muscularis propria or muscularis mucosa. Eligible patients with suspected small (≤ 20 mm) GISTs were included for analysis. Patients’ demographic data, lesions’ characteristics, and follow-up medical records were collected.

RESULTS

A total of 383 patients (male/female, 121/262; mean age, 54 years) with 410 suspected small gastric GISTs (1 lesion in 362 patients, 2 lesions in 16, 3 lesions in 4, and 4 lesions in 1) were included for analysis. The most common location was gastric fundus (56.6%), followed by body (29.0%), cardia (12.2%), and antrum (2.2%). After a median follow-up of 28 mo (interquartile range, 16-48; range, 3-156), 402 lesions (98.0%) showed no changes in size, and size of 8 lesions (2.0%) was increased (mean increment, 10 mm). Of the 8 lesions with size increment, endoscopic or surgical resection was performed in 6 patients (5 GISTs and 1 leiomyoma). For other 2 remaining patients, unroofing biopsy or endoscopic ultrasound-guided fine-needle aspiration was carried out (2 GISTs), while no further change in size was noted over a period of 62-64 mo.

CONCLUSION

The majority of suspected small (≤ 20 mm) gastric GISTs had no size increment during follow-up. Regular endoscopic follow-up without pathological diagnosis may be highly helpful for such small gastric subepithelial lesions.

Identification of gastrointestinal stromal tumors from leiomyomas in the esophagogastric junction: A single-center review of 136 cases

To identify significant clinical and CT features for the differentiation of gastrointestinal stromal tumors (GISTs) from leiomyomas in the esophagogastric junction (EGJ).One hundred thirty six patients with pathologically proven GISTs (n = 87) and leiomyomas (n = 49) in the EGJ were enrolled. And preoperative CT images were available in 73 GISTs cases and 34 leiomyoma cases. Two radiologists reviewed the CT images by consensus with regard to tumor size, shape, growth pattern, surface, enhancement pattern, enhancement degree, attention at each phasic image and the presence of surface ulcer, calcification, and intralesional low attention.Eight significant clinical and CT features were identified for differentiating GISTs from leiomyomas: older age (>46.5 years), tumor long diameter >4.5 cm, heterogeneous enhancement, high degree enhancement, mean CT attenuation >69.2 HU, presences of intralesional low attenuation and surface ulcer, absences of calcification (P < .05). On the receiver operating characteristic curve analysis, an optimal cutoff score of 3.5 was achieved for differentiating GISTs from leiomyomas with an AUC of 0.844 (sensitivity: 76.7%, specificity: 76.5%).older age (>46.5 years), tumor long diameter >4.5 cm, heterogeneous enhancement, high degree enhancement, mean CT attenuation >69.2 HU, presences of intralesional low attenuation and surface ulcer, absence of calcification are significant features highly suggestive of GISTs in differentiation from leiomyomas in the EGJ.

The Use of Molecular Subtypes for Precision Therapy of Recurrent and Metastatic Gastrointestinal Stromal Tumor

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumor in the digestive tract. Tyrosine kinase inhibitors (TKIs), represented by imatinib, sunitinib, and regorafenib, have become the main treatment for recurrent and metastatic GISTs. With the wide application of mutation analysis and the precision medicine, molecular characteristics have been determined that not only predict the prognosis of patients with recurrent and metastatic GISTs, but also are closely related to the efficacy of first-, second- and third-line TKIs for GISTs, as well as other TKIs. Despite the significant effects of TKIs, the emergence of primary and secondary resistance ultimately leads to treatment failure and tumor progression. Currently, due to the signal transmission of KIT/PDGFRA during onset and tumor progression, strategies to counteract drug resistance include the replacement of TKIs and the development of new drugs that are directed towards carcinogenic mutations. In addition, it is also the embodiment of precision medicine for GISTs to explore new carcinogenic mechanisms and develop new drugs relying on new biotechnology. Surgery can benefit specific patients but its major purpose is to diminish the resistant clones. However, the prognosis of recurrent and metastatic patients is still unsatisfactory. Therefore, it is worth paying attention to how to maximize the benefits for patients.

Decoding the Genomic Report for Radiologists

OBJECTIVE. The purpose of this review is to provide a guide for radiologists that explains the language and format of modern genomic reports and summarizes the relevance of this information for modern oncologic imaging. CONCLUSION. Genomic testing plays a critical role in guiding oncologic therapies in the age of targeted treatments. Understanding and interpreting genomic reports is a valuable skill for radiologists involved with oncologic imaging interpretation.

Efficacy and Safety of Endoscopic Treatment for Gastrointestinal Stromal Tumors in the Upper Gastrointestinal Tract

Background/Aims:

Endoscopic treatment (ET) has been applied for decades to treat subepithelial tumors, including gastrointestinal stromal tumors (GISTs). However, the efficacy of ET remains debatable. In this study, we evaluated the efficacy and safety of ET for GISTs in the upper gastrointestinal tract.

Methods:

This retrospective single-center study included 97 patients who underwent ET. All patients were enrolled from July 2014 to July 2018. Parameters such as demographics, size, resection margin, complications, pathological features, procedure time, total cost, and follow-up were investigated and analyzed.

Results:

Our study achieved 100% en bloc resection and 77.4% (72/93) R0 resection. The most common location was the fundus with a mean tumor size of 2.1±1.4 cm. The mean age, procedure time, hospital stay, and cost were 59.7±11.3 years, 64.7±35.2 minutes, 6.8 days, and 5,337 dollars, respectively. According to National Institutes of Health classification, 63 (64.9%), 26 (26.8%), 5 (5.2%), and 3 (3.1%) patients belonged to the very low, low, intermediate, and high risk classification, respectively. Immunohistochemistry results showed a 100% positive rate of CD34, DOG-1, CD117, and Ki67. A mean follow-up of 21.3±13.0 months showed no recurrence or metastasis.

Conclusions:

ET is effective and safe for curative removal of GISTs in the upper gastrointestinal tract, and it can be a treatment of choice for patients with no metastasis.

TAS-116 inhibits oncogenic KIT signalling on the Golgi in both imatinib-naïve and imatinib-resistant gastrointestinal stromal tumours

BACKGROUND

Despite the effectiveness of imatinib mesylate (IM), most gastrointestinal stromal tumours (GISTs) develop IM resistance, mainly due to the additional kinase-domain mutations accompanied by concomitant reactivation of KIT tyrosine kinase. Heat-shock protein 90 (HSP90) is one of the chaperone molecules required for appropriate folding of proteins such as KIT.

METHODS

We used a novel HSP90 inhibitor, TAS-116, which showed specific binding to HSP90α/β with low toxicity in animal models. The efficacy and mechanism of TAS-116 against IM-resistant GIST were evaluated by using IM-naïve and IM-resistant GIST cell lines. We also evaluated the effects of TAS-116 on the other HSP90 client protein, EGFR, by using lung cell lines.

RESULTS

TAS-116 inhibited growth and induced apoptosis in both IM-naïve and IM-resistant GIST cell lines with KIT activation. We found KIT was activated mainly in intracellular compartments, such as trans-Golgi cisternae, and TAS-116 reduced autophosphorylated KIT in the Golgi apparatus. In IM-resistant GISTs in xenograft mouse models, TAS-116 caused tumour growth inhibition. We found that TAS-116 decreased phosphorylated EGFR levels and inhibited the growth of EGFR-mutated lung cancer cell lines.

CONCLUSION

TAS-116 may be a novel promising drug to overcome tyrosine kinase inhibitor-resistance in both GIST and EGFR-mutated lung cancer.

Role of 18F-FDG PET/CT in restaging and follow-up of patients with GIST

PURPOSE

Gastrointestinal stromal tumor (GIST) is a rare tumor with high risk of recurrence and poor prognosis in case of advanced GIST. The aim of this study was to evaluate the possible role of 18F-FDG PET/CT in restaging GIST.

METHODS

Fifty-four patients (30 male) with histological proven GIST underwent 100 18F-FDG PET/CT for restaging in suspected recurrence or during follow-up. Histopathology results and/or clinical/imaging follow-up for at least 12 months were considered as reference standard. Moreover, the diagnostic accuracy and clinical impact of 18F-FDG PET/CT were calculated.

RESULTS

Twenty-seven (27%) 18F-FDG PET/CT were positive, while the remaining 73 (73%) were negative. Sensitivity, specificity, PPV, NPV, and accuracy of PET/CT were 89% (95% CI 72-98%), 97% (95% CI 90-100%), 93% (95% CI 76-98%), 96% (95% CI 89-98%), and 95% (95% CI 89-98%). 18F-FDG PET/CT had a positive clinical impact in 18/100 studies changing the management, in 8 cases switching from local therapy to systemic therapy due to the detection of disseminate disease at PET/CT, in three cases recognizing relapse not detected by conventional imaging, and in 7 cases demonstrating to be true negative and avoiding unnecessary therapies.

CONCLUSIONS

18F-FDG PET/CT seems to be an accurate method for detection and localization of local and distant recurrence in GIST with good sensitivity and specificity and significant impact on clinical decision-making.

CT-Based Radiomic Signature as a Prognostic Factor in Stage IV ALK-Positive Non-small-cell Lung Cancer Treated With TKI Crizotinib: A Proof-of-Concept Study

Objectives: To identify a computed tomography (CT)-based radiomic signature for predicting progression-free survival (PFS) in stage IV anaplastic lymphoma kinase (ALK)-positive non-small-cell lung cancer (NSCLC) patients treated with tyrosine kinase inhibitor (TKI) crizotinib. Materials and Methods: This retrospective proof-of-concept study included a cohort of 63 stage IV ALK-positive NSCLC patients who had received TKI crizotinib therapy for model construction and validation. Another independent cohort including 105 stage IV EGFR-positive NSCLC patients was also used for external validation in EGFR-TKI treatment. We initially extracted 481 quantitative three-dimensional features derived from manually segmented tumor volumes of interest. Pearson's correlation analysis along with the least absolute shrinkage and selection operator (LASSO) penalized Cox proportional hazards regression was successively performed to select critical radiomic features. A CT-based radiomic signature for PFS prediction was obtained using multivariate Cox regression. The performance evaluation of the radiomic signature was conducted using the concordance index (C-index), time-dependent receiver operating characteristic (ROC) analysis, and Kaplan-Meier survival analysis. Results: A radiomic signature containing three features showed significant prognostic performance for ALK-positive NSCLC patients in both the training cohort (C-index, 0.744; time-dependent AUC, 0.895) and the validation cohort (C-index, 0.717; time-dependent AUC, 0.824). The radiomic signature could significantly risk-stratify ALK-positive NSCLC patients (hazard ratio, 2.181; P < 0.001) and outperformed other prognostic factors. However, no significant association with PFS was captured for the radiomic signature in the EGFR-positive NSCLC cohort (log-rank tests, P = 0.41). Conclusions: The CT-based radiomic features can capture valuable information regarding the tumor phenotype. The proposed radiomic signature was found to be an effective prognostic factor in stage IV ALK mutated nonsynchronous nodules in NSCLC patients treated with a TKI.

Computed tomography-based radiomics model for discriminating the risk stratification of gastrointestinal stromal tumors

PURPOSE

The pathological risk degree of gastrointestinal stromal tumors (GISTs) has become an issue of great concern. Computed tomography (CT) is beneficial for showing adjacent tissues in detail and determining metastasis or recurrence of GISTs, but its function is still limited. Radiomics has recently shown a great potential in aiding clinical decision-making. The purpose of our study is to develop and validate CT-based radiomics models for GIST risk stratification.

METHODS

Three hundred and sixty-six patients clinically suspected of primary GISTs from January 2013 to February 2018 were retrospectively enrolled, among which data from 140 patients were eventually analyzed after exclusion. Data from patient CT images were partitioned based on the National Institutes of Health Consensus Classification, including tumor segmentation, radiomics feature extraction and selection. A radiomics model was then proposed and validated.

RESULTS

The radiomics signature demonstrated discriminative performance for advanced and nonadvanced GISTs with an area under the curve (AUC) of 0.935 [95% confidence interval (CI) 0.870-1.000] and an accuracy of 90.2% for validation cohort. The radiomics signature demonstrated favorable performance for the risk stratification of GISTs with an AUC of 0.809 (95% CI 0.777-0.841) and an accuracy of 67.5% for the validation cohort. Radiomics analysis could capture features of the four risk categories of GISTs. Meanwhile, this CT-based radiomics signature showed good diagnostic accuracy to distinguish between nonadvanced and advanced GISTs, as well as the four risk stratifications of GISTs.

CONCLUSION

Our findings highlight the potential of a quantitative radiomics analysis as a complementary tool to achieve an accurate diagnosis for GISTs.

Clinical value of next generation sequencing of plasma cell-free DNA in gastrointestinal stromal tumors

Background

Gastrointestinal stromal tumor (GIST) initiation and evolution is commonly framed by KIT/PDGFRA oncogenic activation, and in later stages by the polyclonal expansion of resistant subpopulations harboring KIT secondary mutations after the onset of imatinib resistance. Thus, circulating tumor (ct)DNA determination is expected to be an informative non-invasive dynamic biomarker in GIST patients.

Methods

We performed amplicon-based next-generation sequencing (NGS) across 60 clinically relevant genes in 37 plasma samples from 18 GIST patients collected prospectively. ctDNA alterations were compared with NGS of matched tumor tissue samples (obtained either simultaneously or at the time of diagnosis) and cross-validated with droplet digital PCR (ddPCR).

Results

We were able to identify cfDNA mutations in five out of 18 patients had detectable in at least one timepoint. Overall, NGS sensitivity for detection of cell-free (cf)DNA mutations in plasma was 28.6%, showing high concordance with ddPCR confirmation. We found that GIST had relatively low ctDNA shedding, and mutations were at low allele frequencies. ctDNA was detected only in GIST patients with advanced disease after imatinib failure, predicting tumor dynamics in serial monitoring. KIT secondary mutations were the only mechanism of resistance found across 10 imatinib-resistant GIST patients progressing to sunitinib or regorafenib.

Conclusions

ctDNA evaluation with amplicon-based NGS detects KIT primary and secondary mutations in metastatic GIST patients, particularly after imatinib progression. GIST exhibits low ctDNA shedding, but ctDNA monitoring, when positive, reflects tumor dynamics.

Resection of the gastric submucosal tumor (G-SMT) originating from the muscularis propria layer: comparison of efficacy, patients' tolerability, and clinical outcomes between endoscopic full-thickness resection and surgical resection

Background and aims

Endoscopic full-thickness resection (EFTR) has been increasingly applied in the treatment of gastric submucosal tumors (G-SMTs) with explorative intention. This study aimed to compare the efficacy, tolerability, and clinical outcomes of EFTR and surgical intervention for the management of muscularis propria (MP)-derived G-SMTs.

Methods

Between September 2011 and May 2019, the clinical records of patients with MP-derived G-SMTs undergoing EFTR at our endoscopic unit were collected. A cohort of people with primary MP-derived G-SMTs treated by surgery was matched in a 1:1 ratio to EFTR group with regard to patients’ baseline characteristics, clinicopathologic features of the tumor and the procedure date. The perioperative outcomes and follow-up data were analyzed.

Results

In total, 62 and 62 patients were enrolled into the surgery and EFTR group, respectively, with median follow-up of 786 days. The size of G-SMTs (with ulceration) ranged from 10 to 90 mm. For patients with tumor smaller than 30 mm, surgery and EFTR group presented comparable procedural success rate (both were 100%), en bloc resection rate (100% vs. 94.7%), tumor capsule rupture rate (0% vs. 5.3%), and pathological R0 resection rate (both were 100%). EFTR had a statistically significant advantage over surgery for estimated blood loss (3.12 ± 5.20 vs. 46.97 ± 60.73 ml, p ≤ 0.001), discrepancy between the pre- and postprocedural hemoglobin level (5.18 ± 5.43 vs. 9.84 ± 8.25 g/L, p = 0.005), bowel function restoration [1 (0–5) vs. 3 (1–5) days, p ≤ 0.001], and hospital cost (28,617.09 ± 6720.78 vs. 33,963.10 ± 13,454.52 Yuan, p = 0.033). The patients with tumor larger than 30 mm showed roughly the same outcomes after comparison analysis of the two groups. However, the clinical data revealed lower en bloc resection rate (75.0% vs. 100%, p = 0.022) and higher tumor capsule rupture rate (25.0% vs. 0%, p = 0.022) for EFTR when compared to surgery. The procedure time, duration of postprocedural fasting and antibiotics usage, and hospital stay of the two groups were equivalent. The occurrence rate of adverse events within postoperative day 7 were 74.2% and 72.6% after EFTR and surgery, respectively (p = 1.000). No complications occurred during the follow-up.

Conclusion

For treatment of MP-derived G-SMTs (with or without ulceration), our study showed the feasibility and safety of EFTR, which also provided better results in terms of procedural blood loss, the postoperative bowel function restoration and cost-effectiveness when compared to surgery, whereas the surgery was superior in en bloc resection rate for G-SMTs larger than 30 mm. The postprocedural clinical outcomes seemed to be equivalent in these two resection methods.

Renal Clearable Theranostic Nanoplatforms for Gastrointestinal Stromal Tumors

Advances in molecular imaging modalities have accelerated the diagnosis and treatment of human diseases. However, tumors less than 1 cm in size still remain difficult to localize by conventional means because of the difficulty in specific targeting/delivery to the tumor site. Furthermore, high nonspecific uptake in the major organs and persistent background retention results in low tumor-to-background ratio. The targeting and therapy of gastrointestinal stromal tumors (GIST) using nonsticky and renal clearable theranostic nanoparticles (a.k.a. H-Dots) are demonstrated. H-Dots not only target GIST for image-guided surgery, but also tailor the fate of anticancer drugs such as imatinib (IM) to the tumor site resulting in efficient treatment of unresectable GIST. In addition, H-Dots can monitor targetability, pharmacokinetics, and drug delivery, while also showing therapeutic efficacy in GIST-bearing xenograft mice following surgical resection. More importantly, IM loaded H-Dots exhibit lower uptake into the immune system, improved tumor selectivity, and increased tumor suppression compared to free IM, which accumulates in the spleen/liver. Precisely designed H-Dots can be used as a promising theranostic nanoplatform that can potentially reduce the side effects of conventional chemotherapies.

Efficacy and safety of endoscopic submucosal dissection for large gastric stromal tumors

BACKGROUND AND AIM

Endoscopic submucosal dissection (ESD) of gastric stromal tumors is becoming increasingly common. However, there have been few studies analyzing the therapeutic efficacy and safety of this technique on large (≥ 3 cm) gastric stromal tumors (LGSTs). The aim of this study was to determine the feasibility of ESD for the removal of LGSTs and to investigate the clinical safety and efficacy of ESD for this indication.

METHODS

A retrospective analysis was carried out on 82 patients with LGSTs who underwent an ESD. Data on therapeutic outcomes and follow-up were collected for an analysis of the rates of en block resection and complete resection. A logistic regression model was used to identify potential risk factors for ESD-related complications, and a receiver operating characteristic (ROC) curve was generated for qualifying independent risk factors.

RESULTS

En bloc resection was achieved in 81 lesions (98.8%), and complete resection was achieved in 80 lesions (97.6%). The rates of intraoperative and postoperative bleeding were 6.1% and 3.7%, respectively. The accidental perforation rate was 12.2%, the postoperative perforation rate was 3.7%, the intentional perforation rate was 28.0%, and the postoperative infection rate was 12.2%. There was no postoperative mortality. LGSTs originating from the deep muscularis propria (MP) layer (OR = 4.905, 95% CI: 1.362-17.658, P = 0.015), located at the gastric fundus (OR = 4.927, 95% CI:1.308-18.558, P = 0.018) and with an irregular shape (OR = 4.842, 95% CI: 1.242-18.870, P = 0.023) increased the rate of complications. The prediction model that incorporated these factors demonstrated an area under the ROC curve of 0.77 (95% CI: 0.66-0.89). No tumor recurrence or distant metastasis was observed during the follow-up period, which ranged from 6-36 months.

CONCLUSIONS

ESD is a feasible, safe, effective and minimally invasive approach for the resection of LGSTs. Tumors originating from the deep MP layer, located at the fundus and with an irregular shape were identified as risk factors for the development of complications.

Bromodomain and extraterminal domain inhibitor enhances the antitumor effect of imatinib in gastrointestinal stromal tumours

In gastrointestinal stromal tumours (GISTs), the function of bromodomain-containing 4 (BRD4) remains underexplored. BRD4 mRNA abundance was quantified in GISTs. In the current study, we investigated the role of BRD4 in GISTs. Our results show a significant enhancement in BRD4 mRNA and a shift from very low-risk/low-risk to high-risk levels as per NCCN specifications. Overexpression of BRD4 correlated with unfavourable genotype, nongastric location, enhanced risk and decreased disease-free survival, which were predicted independently. Knockout of BRD4 in vitro suppressed KIT expression, which led to inactivation of the KIT/PI3K/AKT/mTOR pathway, impeded migration and cell growth and made the resistant GIST cells sensitive to imatinib. The expression of KIT was repressed by a BRD4 inhibitor JQ1, which also induced myristoylated-AKT-suppressible caspases 3 and 9 activities, induced LC3-II, exhibited dose-dependent therapeutic synergy with imatinib and attenuated the activation of the PI3K/AKT/mTOR pathway. In comparison with their single therapy, the combination of JQ1/imatinib more efficiently suppressed the growth of xenografts and exhibited a reduction in KIT phosphorylation, a decrease in Ki-67 and in the levels of phosphorylated PI3K/AKT/mTOR and enhanced TUNEL staining. Thus, we characterized the biological, prognostic and therapeutic implications of overexpressed BRD4 in GIST and observed that JQ1 suppresses KIT transactivation and nullifies the activation of PI3K/AKT/mTOR, providing a potential strategy for treating imatinib-resistant GIST through dual blockade of KIT and BRD4.

Third Space Endoscopy: Lessons Learnt From a Decade of Submucosal Endoscopy

The field of third space endoscopy (TSE), also called submucosal endoscopy using a mucosal flap valve, allows secure access to the submucosal and deeper layers of the gastrointestinal tract without the risk of a full-thickness perforation. Since the first description of per-oral endoscopic myotomy (POEM) for the treatment of achalasia cardia 10 years ago, this field has expanded rapidly. Several new procedures, submucosal tunneling endoscopic resection, gastric-POEM, Zenker POEM, per-rectal endoscopic myotomy, diverticular POEM, and recanalization for complete esophageal obstruction (per-oral endoscopic tunneling for restoration of the esophagus), have been performed. All TSE procedures employ a similar technique-after a mucosal incision, a submucosal tunnel is created, a myotomy is performed, or a subepithelial tumor is resected distal to the site of mucosal incision, after which the mucosal incision is closed. Potential indications for TSE include resection of subepithelial tumors in the esophagus, gastroesophageal junction, or stomach; refractory gastroparesis; Zenker diverticulum; Hirschsprung disease or other forms of megacolon; and recanalization for complete esophageal obstruction. Data are currently available for POEM, submucosal tunneling endoscopic resection, and gastric-POEM, although mainly in the form of retrospective studies, and randomized trials and long-term follow-up data are limited. Submucosal endoscopy has an excellent safety profile with very few intraoperative adverse events, the majority being related to insufflation, although bleeding, perforation, and sepsis have been reported. TSE procedures require special training and have demonstrated a learning curve.

Development and validation of a nomogram based on CT images and 3D texture analysis for preoperative prediction of the malignant potential in gastrointestinal stromal tumors

Background

Gastrointestinal stromal tumors (GISTs), which are the most common mesenchymal tumors of the digestive system, are treated varyingly according to the malignancy. The purpose of this study is to develop and validate a nomogram for preoperative prediction of the malignant potential in patients with GIST.

Methods

A total of 440 patients with pathologically confirmed GIST after surgery in our hospital from January 2011 to July 2019 were retrospectively analyzed. They were randomly divided into the training set (n = 308) and validation set (n = 132). CT signs and texture features of each patient were analyzed and predictive model were developed using the least absolute shrinkage and selection operator (lasso) regression. Then a nomogram based on selected parameters was developed. The predictive effectiveness of nomogram was evaluated by the area under receiver operating characteristic (ROC) curve (AUC). Concordance index (C-index) and calibration plots were formulated to evaluate the reliability and accuracy of the nomogram by bootstrapping based on internal (training set) and external (validation set) validity. The clinical application value of the nomogram was determined through the decision curve analysis (DCA).

Results

Totally 156 GIST patients with low-malignant (very low and low risk) and 284 ones with high-malignant potential (intermediate and high risk) are enrolled in this study. The prediction nomogram consisting of size, cystoid variation and meanValue had an excellent discrimination both in training and validation sets (AUCs (95% confidence interval(CI)): 0.935 (0.908, 0.961), 0.933 (0.892, 0.974); C-indices (95% CI): 0.941 (0.912, 0.956), 0.935 (0.901, 0.982); sensitivity: 81.4, 90.6%; specificity: 75.0, 75.7%; accuracy: 88.0, 88.6%, respectively). The calibration curves indicated a good consistency between the actual observation and nomogram prediction for differentiating GIST malignancy. Decision curve analysis demonstrated that the nomogram was clinically useful.

Conclusion

This study presents a prediction nomogram that incorporates the CT signs and texture parameter, which can be conveniently used to facilitate the preoperative individualized prediction of malignancy in GIST patients.

Use of omental patch and endoscopic closure technique as an alternative to surgery after endoscopic full thickness resection of gastric intestinal stromal tumors: A series of cases

BACKGROUND

Gastrointestinal stromal tumors (GISTs) originate from interstitial cells of Cajal. GISTs can occur anywhere along the gastrointestinal tract. Large lesions have traditionally been removed surgically. However, with recent innovations in advanced endoscopy, GISTs located within the stomach are now removed endoscopically. We describe a new innovative endoscopic technique to close large and hard to access defects after endoscopic full-thickness resection of gastric GISTs.

CASE SUMMARY

We present a series of three patients who were diagnosed with a gastric GIST. All patients underwent full-thickness endoscopic resection. In all cases, for closure of the surgical bed, conventional endoscopic techniques including hemoclips, endoloop and suturing were unsuccessful. We performed a new technique in which we pulled omental fat into the gastric lumen and completely closed the defect using endoscopic devices. All patients performed well post-procedure and computed tomography was carried out one day after the procedures which showed no extravasation of contrast.

CONCLUSION

The omental plug technique may be used as an alternative to surgery in selected cases of gastric perforation.

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

Background:

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

Methods:

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

Results:

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

Conclusion:

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