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

Artificial Intelligence in the Pathology of Gastric Cancer

Recent advances in artificial intelligence (AI) have provided novel tools for rapid and precise pathologic diagnosis. The introduction of digital pathology has enabled the acquisition of scanned slide images that are essential for the application of AI. The application of AI for improved pathologic diagnosis includes the error-free detection of potentially negligible lesions, such as a minute focus of metastatic tumor cells in lymph nodes, the accurate diagnosis of potentially controversial histologic findings, such as very well-differentiated carcinomas mimicking normal epithelial tissues, and the pathological subtyping of the cancers. Additionally, the utilization of AI algorithms enables the precise decision of the score of immunohistochemical markers for targeted therapies, such as human epidermal growth factor receptor 2 and programmed death-ligand 1. Studies have revealed that AI assistance can reduce the discordance of interpretation between pathologists and more accurately predict clinical outcomes. Several approaches have been employed to develop novel biomarkers from histologic images using AI. Moreover, AI-assisted analysis of the cancer microenvironment showed that the distribution of tumor-infiltrating lymphocytes was related to the response to the immune checkpoint inhibitor therapy, emphasizing its value as a biomarker. As numerous studies have demonstrated the significance of AI-assisted interpretation and biomarker development, the AI-based approach will advance diagnostic pathology.

Reliability of endoscopic ultrasonography and endoscopy in measurement of gastric subepithelial tumor size

BACKGROUND

Subepithelial tumor (SET) size is important in determining the treatment plan; however, size estimation for gastric SETs has not been well investigated. We aimed to investigate which method predicts SET size most accurately by retrospectively analyzing surgically removed SETs.

METHODS

From January 2015 through June 2020, patients who underwent surgical gastric SET removal at Asan Medical Center, Seoul, Korea, were enrolled. SET sizes measured by pathologists and endoscopists were retrospectively reviewed. The reliability of SET size measurement by endoscopic ultrasonography (EUS) and endoscopy was calculated using intraclass correlation coefficient (ICC), with pathologic size as the gold standard.

RESULTS

Overall, EUS was highly reliable (ICC 0.86, P < 0.001), and endoscopy was moderately reliable (ICC 0.75, P < 0.001). When analyzed according to SET location, endoscopy was highly reliable in the lesser curvature's lower third (ICC 0.86, P = 0.014), middle third (ICC 0.88, P < 0.001), and upper third (ICC 0.90, P < 0.001); as well as the anterior wall's middle third (0.84, P < 0.001) and the posterior wall's upper third (ICC 0.80, P < 0.001). EUS (ICC 0.96, P = 0.005) and endoscopy (ICC 0.95, P = 0.008) both were most reliable for lower-third posterior wall lesions, whereas endoscopy was unreliable for middle-third greater curvature lesions (ICC 0.41, P = 0.05).

CONCLUSIONS

Both EUS and endoscopy were reliable methods for measuring gastric SET size, and overall, EUS was more reliable than endoscopy. In terms of SET location, EUS was consistently reliable, whereas endoscopy showed variable reliability. When measuring SET size by endoscopy, additional size measurements with EUS should be considered in certain locations.

Endoscopic Resection of Gastrointestinal Stromal Tumor: Is It Safe?

Recently, results from clinical studies of endoscopic resection of gastrointestinal stromal tumor (GIST) in the stomach are being reported. This procedure has several advantages, such as the provision of a definite diagnosis and therapeutic plan, avoidance of frequent follow-up examination, and reduction of patients’ anxiety. However, several concerns also exist such as a limited number of studies, low R0 resection rate, and relatively shorter follow-up period compared with surgical resection. Nevertheless, it is encouraging that most of the post-procedural complications have been treated with conservative management and that some of the patients did not show recurrence of the tumor during long-term follow-up. The selection of suitable cases and the experience of the endoscopists are the most important factors for successful endoscopic resection of gastric GIST. Development of novel procedures as well as collaboration with laparoscopic surgeons are currently in progress.

Standardization of the pathologic diagnosis of appendiceal mucinous neoplasms

Although the understanding of appendiceal mucinous neoplasms (AMNs) and their relationship with disseminated peritoneal mucinous disease have advanced, the diagnosis, classification, and treatment of AMNs are still confusing for pathologists and clinicians. The Gastrointestinal Pathology Study Group of the Korean Society of Pathologists (GPSG-KSP) proposed a multicenter study and held a workshop for the “Standardization of the Pathologic Diagnosis of the Appendiceal Mucinous Neoplasm” to overcome the controversy and potential conflicts. The present article is focused on the diagnostic criteria, terminologies, tumor grading, pathologic staging, biologic behavior, treatment, and prognosis of AMNs and disseminated peritoneal mucinous disease. In addition, GPSG-KSP proposes a checklist of standard data elements of appendiceal epithelial neoplasms to standardize pathologic diagnosis. We hope the present article will provide pathologists with updated knowledge on how to handle and diagnose AMNs and disseminated peritoneal mucinous disease.

Preoperative imaging of gastric GISTs underestimates pathologic tumor size: A retrospective, single institution analysis

BACKGROUND

How well imaging size agrees with pathologic size of gastric gastrointestinal stromal tumors (GISTs) is unknown. GIST risk stratification is based on pathologic size, location, and mitotic rate. To inform decision making, the size discrepancy between imaging and pathology for gastric GISTs was investigated.

METHODS

Imaging and pathology reports were reviewed for 113 patients. Bland-Altman analyses and intraclass correlation (ICC) assessed agreement of imaging and pathology. Changes in clinical risk category due to size discrepancy were identified.

RESULTS

Computed tomography (CT) (n = 110) and endoscopic ultrasound (EUS) (n = 50) underestimated pathologic size for gastric GISTs by 0.42 cm, 95% confidence interval (CI): (0.11, 0.73), p = 0.008 and 0.54 cm, 95% CI: (0.25, 0.82), p < 0.001, respectively. ICCs were 0.94 and 0.88 for CT and EUS, respectively. For GISTs ≤ 3 cm, size underestimation was 0.24 cm for CT (n = 28), 95% CI: (0.01, 0.47), p = 0.039 and 0.56 cm for EUS (n = 26), 95% CI: (0.27, 0.84), p < 0.0001. ICCs were 0.72 and 0.55 for CT and EUS, respectively. Spearman's correlation was ≥0.84 for all groups. For GISTs ≤ 3 cm, 6/28 (21.4% p = 0.01) on CT and 7/26 (26.9% p = 0.005) on EUS upgraded risk category using pathologic size versus imaging size. No GISTs ≤ 3 cm downgraded risk categories. Size underestimation persisted for GISTs ≤ 2 cm on EUS (0.39 cm, 95% CI: [0.06, 0.72], p = 0.02, post hoc analysis).

CONCLUSION

Imaging, particularly EUS, underestimates gastric GIST size. Caution should be exercised using imaging alone to risk-stratify gastric GISTs, and to decide between surveillance versus surgery.

Laparoscopic Local Resection through Subserosal Dissection with Endoscopic Air-Insufflation for Submucosal Tumors Located Near the Esophagogastric Junction

Purpose

A novel resection method, namely, laparoscopic local resection through subserosal dissection with endoscopic air-insuff lation (LRSDEA) was used for submucosal tumors located near the esophagogastric junction (SMT-EGJ) to avoid major gastric resection.

Methods

A total of 9 cases underwent LRSDEA. We sequentially performed: laparoscopic dissections around EGJ, subserosal dissections around SMTs using laparoscopic electrocautery and ultrasonic shears, and finally, enucleation of SMTs. During these procedures, intraoperative endoscopic tumor localization, as well as endoscopic air-insufflation allowed for safe resection. These procedures are shown in the supplementary video clip. The clinicopathological characteristics and surgical results were analyzed.

Results

All laparoscopic procedures were successfully performed without requiring a major gastrectomy. The mean operation time was 126.1 minutes, and estimated blood loss was 12.0 ml. There were no postoperative complications. Pathological diagnoses were 6 leiomyomas, 2 gastrointestinal stromal tumors, and 1 gastric duplication.

Conclusion

LRSDEA is an effective and safe treatment option for SMT-EGJ, as major resection of the stomach is avoided.

Gastrointestinal stromal tumours of stomach: Robot-assisted excision with the da Vinci Surgical System regardless of size and location site

Aims:

The role of minimally invasive surgery of gastrointestinal stromal tumours (GISTs) of the stomach remains uncertain especially for large and/or difficult located tumours. We are hereby presenting a single-centre series of robot-assisted resections using the da Vinci Surgical System (Si or Xi).

Subjects and Methods:

Data of patients undergoing robot-assisted treatment of gastric GIST were retrieved from the prospectively collected institutional database and a retrospective analysis was performed. Patients were stratified according to size and location of the tumour. Difficult cases (DCs) were considered for size if tumour was >50 mm and/or for location if the tumour was Type II, III or IV sec. Privette/Al-Thani classification.

Results:

Between May 2010 and February 2017, 12 consecutive patients underwent robot-assisted treatment of GIST at our institution. DCs were 10/12 cases (83.3%), of which 6/10 (50%) for location, 2/10 (25%) for size and 2/10 (25%) for both. The da Vinci Si was used in 8 patients, of which 6 (75%) were DC, and the da Vinci Xi in 4, all of which (100%) were DC. In all patients, excision was by wedge resection. All lesions had microscopically negative resection margins. There was no conversion to open surgery, no tumour ruptures or spillage and no intraoperative complications.

Conclusion:

Our experience suggests a positive role of the robot da Vinci in getting gastric GIST removal with a conservative approach, regardless of size and location site. Comparative studies with a greater number of patients are necessary for a more robust assessment.

Long-Term Outcomes after Endoscopic Treatment of Gastric Gastrointestinal Stromal Tumor

Endoscopic resection of gastric subepithelial tumors (SETs) has several advantages over biopsy techniques, such as superior diagnostic yield and definite diagnosis. Removal of gastric SETs and histopathologic confirmation should be considered whenever gastric SETs are highly suspected to have malignant potential such as gastrointestinal stromal tumor (GIST) or neuroendocrine tumor. According to our clinical experience, we suggest that endoscopic resection of gastric SETs is feasible for GISTs less than 3.0 cm without positive endoscopic ultrasonography findings or for hypoechoic SETs less than 3.0 cm. However, serious complications such as macroperforation may occur during endoscopic resection, and this procedure is highly dependent on endoscopists’ skills. We recently reported the long-term clinical outcomes of endoscopic resection of gastric GIST, which showed a relatively low recurrence rate (2.2%) during long-term follow-up (46.0±28.5 months) despite the low R0 resection rate (25.0%). We suggest that endoscopic surveillance might be possible without additional surgical resection in completely resected GISTs without residual tumor confirmed to be lower risk, even if they show an R1 resection margin.

Endoscopic and Laparoscopic Full-Thickness Resection of Endophytic Gastric Submucosal Tumors Very Close to the Esophagogastric Junction

Purpose

Gastric submucosal tumors (SMTs) located very close to the esophagogastric junction (EGJ) are a challenge for gastric surgeons. Therefore, this study reports on the experience of using endoscopic and laparoscopic full-thickness resection (ELFR) with laparoscopic two-layer suturing in such tumors.

Materials and Methods

Six patients with gastric SMTs very close to the EGJ underwent ELFR with laparoscopic two-layer suturing at Kyungpook National University Medical Center. With the patient under general anesthesia, the lesser curvature and posterior aspect adjacent to the EGJ were meticulously dissected and visualized using a laparoscopic approach. A partially circumferential full-thickness incision at the distal margin of the tumor was then made using an endoscopic approach under laparoscopic guidance. The SMT was resected using laparoscopic ultrasonic shears, and the gastric wall was closed using two-layer suturing. Thereafter, the patency and any leakage were checked through endoscopy.

Results

All the ELFR procedures with laparoscopic two-layer suturing were performed successfully without an open conversion. The mean operation time was 139.2±30.9 minutes and the blood loss was too minimal to be measured. The tumors from four patients were leiomyomas, while the tumors from the other two patients were gastrointestinal stromal tumors with clear resection margins. All the patients started oral intake on the third postoperative day. There was no morbidity or mortality. The mean hospital stay was 7.7±0.8 days.

Conclusions

ELFR with laparoscopic two-layer suturing is a safe treatment option for patients with an SMT close to the EGJ, as major resection of the stomach is avoided.

Laparoscopic surgery for gastric gastrointestinal stromal tumor is feasible irrespective of tumor size

PURPOSE

To compare the outcomes of laparoscopic surgery and open surgery for gastric gastrointestinal stromal tumors (GISTs) by size-matched analysis and evaluate whether laparoscopic surgery for lesions of >5 cm is feasible.

PATIENTS AND METHODS

Data of 44 consecutive patients with gastric GIST who underwent surgery from 1988 to 2011 were reviewed. Twenty-three patients who underwent successful laparoscopic surgery were compared with 10 patients with similar tumor sizes who underwent open surgery. Among the 23 patients in the laparoscopic group, we compared postoperative results between GISTs of ≤5 cm and >5 cm.

RESULTS

There were no differences in clinicopathological characteristics between the laparoscopic surgery group (LG) and the open surgery group (OG). The operation time was not different, but the blood loss (5.5 mL [range, 0-425 mL] in LG and 125 mL [range, 0-676 mL] in OG) (P=.008) and postoperative hospital stay (21 days in OG and 8 days in LG) (P<.001) were significantly less in the LG. Postoperative complications and recurrence were not different. Comparison between patients with lesions of >5 cm and patients with smaller lesions in the LG found that smaller lesions were associated with a shorter postoperative hospital stay (7.5 days versus 11 days) (P=.037).

CONCLUSIONS

Laparoscopic resection of primary gastric GISTs is feasible even for tumors of >5 cm.

Application of blunt dissection in ESD of a gastric submucosal tumor

We performed endoscopic submucosal dissection of a gastric fundus tumor. It was difficult to strip the tumor completely due to space limitation, and we used blunt dissection to remove the tumor quickly and safely. Firstly, the basal area of the 2.5 cm submucosal tumor located in the gastric fundus was cut open, and the mucosa was dissected. The tumor was difficult to peel, therefore, a snare was used and the tumor was pulled and tightened slightly. Short electronic coagulation was used during the procedure. The tumor was then bluntly dissected. This method ensured rapid and complete removal of the tumor.

Expression and clinicopathological significance of CD9 in gastrointestinal stromal tumor

This study investigated the expression and clinicopathological significance of CD9 in gastrointestinal stromal tumor (GIST). Immunohistochemistry staining for CD9 was performed on tumor tissues from 74 GIST patients. The correlation with clinicopathological features, risk classification and prognosis was analyzed. CD9-positive staining comprised 59.5% (44/74) of the GIST patients. The CD9-positive expression rate of the sample was significantly associated with diameter (P = 0.028), mitotic counts (P = 0.035), risk classification (P = 0.018) and three-year recurrence-free survival (RFS) (P < 0.001). Cox proportional hazards regression (HR = 0.352; P = 0.015) showed that CD9 is an independent factor for post-operative RFS. The subgroup analysis showed that CD9 expression in gastric stromal tumor (GST) is significantly associated with diameter (P = 0.031), risk classification (P = 0.023) and three-year RFS (P = 0.001). The Cox proportional hazards regression (HR = 0.104; P = 0.006) also showed that CD9 is an independent factor for RFS of GST. However, CD9 expression does not have a statistically significant correlation with clinicopathological features, risk classification, and prognosis in non-GST. In conclusion, CD9 expression in GIST appears to be associated with the recurrence and/or metastasis of GIST patients, especially in GST, which may indicate the important role of CD9 in the malignant biological behavior and prognosis of GST.

[Gastroduodenal intussusception due to pedunculated polypoid gastrointestinal stromal tumor]

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

Laparoscopic and robotic distal gastrectomy for gastrointestinal stromal tumour: case report

BACKGROUND

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours of the digestive tract. The most frequent site of occurrence is the stomach. Due to the high potential for malignancy of GIST, resection should be the first-line treatment. Minimally invasive surgery may be used for surgical resection of GISTs.

METHODS

We describe a case of laparoscopic and robotic distal gastrectomy in a patient with diagnosis of GIST in the gastric antrum. Laparoscopy was useful for dissection and a da Vinci robot was used for Roux-en-Y reconstruction.

RESULTS

The postoperative course was uneventful.

CONCLUSIONS

Minimally invasive surgery offers benefits compared to open surgery, and laparoscopic and robot-assisted gastrectomy for the treatment of GIST could be technically feasible and safe because of the advantageous movements provided by the robotic arms.

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

Despite their rarity in incidence and prevalence, gastrointestinal stromal tumors (GISTs) have emerged as a distinct and noteworthy pathogenetic entity. The clinical management of GISTs has rapidly evolved due to the recent elucidation of their oncogenic signal transduction pathway and the introduction of molecular-targeted therapies. Successful management of GISTs requires a multidisciplinary approach firmly based on an accurate histopathologic diagnosis. In 2007, the Korean GIST study group published the first guideline for optimal diagnosis and treatment of GISTs in Korea. The second version of the guideline was published in 2010. Herein, we provide the results of relevant clinical studies for the purpose of further revision to the guideline. We expect this new guideline will enhance the accuracy of diagnosis, as performed by members of the Korean associate of physicians involved in GIST patient care, thus improving the efficacy of treatment.

Clinicopathologic change of gastrointestinal stromal tumor after neoadjuvant imatinib followed by surgical resection

A 53-year-old woman was diagnosed with gastrointestinal stromal tumor (GIST) of the stomach. Computed tomography (CT) revealed a huge mass (12 cm in diameter), likely to invade pancreas and spleen. In the operation field, the tumor was in an unresectable state. The patient was then started on imatinib therapy for 4 months. On follow-up imaging studies, the tumor almost disappeared. We performed total gastrectomy and splenectomy upon which two small-sized residual tumors were found on microscopy. In this paper, we describe a case of clinicopathologic change in unresectable GIST after neoadjuvant imatinib mesylate.

Sorafenib in patients with metastatic gastrointestinal stromal tumors who failed two or more prior tyrosine kinase inhibitors: a phase II study of Korean gastrointestinal stromal tumors study group

PURPOSE

To evaluated the efficacy and safety of sorafenib in patients with advanced gastrointestinal stromal tumors (GIST) who failed to previous standard treatments.

EXPERIMENTAL DESIGN

Thirty-one patients with measurable metastatic GIST who failed both imatinib and sunitinib were accrued. Sorafenib was administered orally at 400 mg twice daily until disease progression or development of intolerance. The primary endpoint was disease control rate (response + stable disease, DCR) at 24 weeks.

RESULTS

Sorafenib was well tolerated, with hand-foot skin reaction, fatigue, hypertension, and abdominal pain being the most frequent adverse events. The relative dose intensity of sorafenib during the first 6 months was >80%. Four patients achieved partial response (response rate 13%, 95% CI 1-25%), and 16 (52%) had stable disease. DCR at 24 weeks was measured as 36% (95% CI 19-52%). Median progression-free and overall survivals were 4.9 and 9.7 months, respectively. Progression-free survival of patients with prior use of nilotinib (P = .0085) and with primary genotypes other than KIT exon 11 mutation (P = .0341) was significantly shorter than that of patients without.

CONCLUSIONS

Sorafenib showed antitumor activity in this population of imatinib and sunitinib pretreated GIST. With sorafenib, about one third of patients can maintain disease control for more than 24 weeks.

Clinical impact of EUS-guided Trucut biopsy results on decision making for patients with gastric subepithelial tumors ≥ 2 cm in diameter

BACKGROUND

Preoperative pathologic diagnosis of a gastric subepithelial tumor (SET) may improve clinical decision making. However, the clinical impact of EUS-guided Trucut biopsy (EUS-TCB) data on decision making in patients with a gastric SET has not been assessed.

OBJECTIVE

To evaluate the impact of EUS-TCB information on the clinical management of patients with a gastric SET.

DESIGN

Retrospective review of prospectively collected data.

SETTING

Tertiary referral center.

PATIENTS

Sixty-five patients with gastric SETs 2 cm or larger in diameter.

INTERVENTION

EUS-TCB.

MAIN OUTCOME MEASUREMENTS

The number of patients for whom treatment plans were changed because of EUS-TCB results.

RESULTS

Nine SETs were not punctured by the TCB needle because of technical problems, and we were unable to obtain adequate subepithelial tissue from 19 SETs. Treatment plans were changed for 18 of 65 patients (27.7%). The changes were avoiding unnecessary resection (7 benign SETs ≥ 3 cm in diameter), scheduling for definitive treatment (6 GI stromal tumors and 1 carcinoid tumor), and modifying the surgical field (3 large GI stromal tumors and 1 carcinoma). When we assessed treatment plans relative to tumor location, we found that avoiding unnecessary resection was associated with the presence of cardiac SETs.

LIMITATIONS

Retrospective study with a small number of patients.

CONCLUSIONS

EUS-TCB changed or influenced management decisions in 18 of 65 patients (27.7%) with gastric SETs. Patients could receive proper and tailored surgery, medical treatment, or surveillance according to size and location of SETs with EUS-TCB.

Response to imatinib rechallenge in a patient with a recurrent gastrointestinal stromal tumor after adjuvant therapy: a case report

Introduction

Adjuvant imatinib improves recurrence-free survival of patients following resection of primary KIT-positive gastrointestinal stromal tumors. However, it is unknown whether patients who previously received adjuvant imatinib therapy will respond to imatinib rechallenge as treatment for recurrent disease. Here we present the first report documenting the benefits of imatinib rechallenge in a patient previously exposed to imatinib during adjuvant treatment.

Case presentation

A 51-year-old Asian woman with a wedge-resected primary gastric gastrointestinal stromal tumor at high risk of relapse underwent two years of adjuvant treatment with imatinib. Only 10 months after the completion of adjuvant imatinib treatment, a computed tomography scan revealed gastrointestinal stromal tumor recurrence in this patient, with multiple peritoneal nodules in the upper abdomen being detected. Our patient was rechallenged with imatinib 400 mg/day and had a partial response after one month of treatment. Imatinib rechallenge was well tolerated by our patient; the only adverse events she experienced were grade 1 edema, anemia and fatigue. Our patient maintained a partial response two years and six months after the imatinib rechallenge. However, computed tomography scans three months later showed that our patient had disease progression.

Conclusions

This case report demonstrates that a patient with a gastrointestinal stromal tumor who had previously received adjuvant imatinib therapy responded to imatinib rechallenge as treatment for her recurrent disease. These results indicate that imatinib sensitivity can be maintained in a patient with previous exposure to adjuvant imatinib therapy.

Efficacy of imatinib mesylate neoadjuvant treatment for a locally advanced rectal gastrointestinal stromal tumor

Surgery is the standard treatment for a primary gastrointestinal stromal tumor (GIST); however, surgical resection is often not curative, particularly for large GISTs. In the past decade, with imatinib mesylate (IM), management strategies for GISTs have evolved significantly, and now IM is the standard care for patients with locally advanced, recurrent or metastatic GISTs. Adjuvant therapy with imatinib was recently approved for use, and preoperative imatinib is an emerging treatment option for patients who require cytoreductive therapy. IM neoadjuvant therapy for primary GISTs has been reported, but there is no consensus on the dose of the drug, the duration of treatment and the optimal time of surgery. These are critical because drug resistance or tumor progression can develop with a prolonged treatment. This report describes two cases of large rectal malignant GISTs, for which a abdominoperineal resection was initially anticipated. The two patients received IM preoperative treatment; we followed-up with CT or magnetic resonance imaging to access the response. After 9 months of treatment, a multi-disciplinary consensus that maximal benefit from imatinib had been achieved was reached. We determined the best time for surgical intervention and successfully performed sphincter-preserving surgery before resistance to imatinib or tumor progression occurred. We believe that a multidisciplinary team approach, considerating the optimal duration of therapy and the timing of surgery, is required to optimize treatment outcome.