Cytoreductive Surgery for Metastatic Gastrointestinal Stromal Tumors Treated With Tyrosine Kinase Inhibitors: A 2-institutional Analysis. Ann Surg. 2018;268:296-302. [PMID: 28448384 DOI: 10.1097/sla.0000000000002281]

English version of Japanese Clinical Practice Guidelines 2022 for gastrointestinal stromal tumor (GIST) issued by the Japan Society of Clinical Oncology

The Japan Society of Clinical Oncology Clinical Practice Guidelines 2022 for gastrointestinal stromal tumor (GIST) have been published in accordance with the Minds Manual for Guideline Development 2014 and 2017. A specialized team independent of the working group for the revision performed a systematic review. Since GIST is a rare type of tumor, clinical evidence is not sufficient to answer several clinical and background questions. Thus, in these guidelines, we considered that consensus among the experts who manage GIST, the balance between benefits and harms, patients' wishes, medical economic perspective, etc. are important considerations in addition to the evidence. Although guidelines for the treatment of GIST have also been published by the National Comprehensive Cancer Network (NCCN) and the European Society for Medical Oncology (ESMO), there are some differences between the treatments proposed in those guidelines and the treatments in the present guidelines because of the differences in health insurance systems among countries.

Cytoreductive surgery in patients with recurrent or metastatic gastrointestinal stromal tumors sensitive to imatinib: a retrospective analysis of two Russian cancer centers

Background

The role of cytoreductive surgery for patients with recurrent or metastatic gastrointestinal stromal tumors (mGISTs) responding to imatinib (IM) has not yet been established. We carried out a retrospective analysis of the outcomes of patients with mGISTs in two Russian cancer centers. We compared two cohorts: treated (Group S) or not treated with surgery (Group NS) after a partial response (PR) or stable disease (SD) while on IM.

Methods

A total 44 patients treated by IM as first line treatment were included in our analysis. Prognostically similar patients only sensitive to IM cases with hepatic or peritoneal metastases as well as durable response to IM lasting more than 12 months were included in a control arm. Patients in Group NS received only IM until disease progression. Patients in Group S were treated additionally with metastasectomy after having response or SD on IM.

Results

The baseline characteristics were similar between the groups with several trends: a higher proportion of patients achieved a PR in Group S (87% vs. 55%, P=0.165), and greater number of patients had peritoneal metastases in Group NS (45% vs. 27%, P=0.759). The median time to surgery from the initiation of IM was 8 months. Progression-free survival (PFS) and overall survival (OS) were significantly longer in Group S than Group NS: the median PFS was 78 vs. 35 months (P=0.088); the median OS was 141 vs. 80 months (P=0.154).

Conclusions

The surgical resection of residual lesions after disease control with IM is likely to be beneficial to patients with mGISTs.

Local treatment in metastatic GIST patients: A multicentre analysis from the Dutch GIST Registry

BACKGROUND

The added value of local treatment in selected metastatic GIST patients is unclear. This study aims to provide insight into the usefulness of local treatment in metastatic GIST by use of a survey study and retrospective analyses in a clinical database.

METHODS

A survey study was conducted among clinical specialists to select most relevant characteristics of metastatic GIST patients considered for local treatment, defined as elective surgery or ablation. Patients were selected from the Dutch GIST Registry. A multivariate Cox-regression model for overall survival since time of diagnosis of metastatic disease was estimated with local treatment as a time-dependent variable. An additional model was estimated to assess prognostic factors since local treatment.

RESULTS

The survey's response rate was 14/16. Performance status, response to TKIs, location of active disease, number of lesions, mutation status, and time between primary diagnosis and metastases, were regarded the 6 most important characteristics. Of 457 included patients, 123 underwent local treatment, which was associated with better survival after diagnosis of metastases (HR = 0.558, 95%CI = 0.336-0.928). Progressive disease during systemic treatment (HR = 3.885, 95%CI = 1.195-12.627) and disease confined to the liver (HR = 0.269, 95%CI = 0.082-0.880) were associated with worse and better survival after local treatment, respectively.

CONCLUSION

Local treatment is associated with better survival in selected patients with metastatic GIST. Locally treated patients with response to TKIs and disease confined to the liver have good clinical outcome. These results might be considered for tailoring treatment, but should be interpreted with care because only specific patients are provided with local treatment in this retrospective study.

SEOM-GEIS clinical guideline for gastrointestinal stromal tumors (2022)

Gastrointestinal stromal tumor (GIST) is the most common malignant neoplasm of mesenchymal origin, and a paradigmatic model for a successful rational development of targeted therapies in cancer. The introduction of tyrosine kinase inhibitors with activity against KIT/PDGFRA in both localized and advanced stages has remarkably improved the survival in a disease formerly deemed resistant to all systemic therapies. These guidelines are elaborated by the conjoint effort of the Spanish Society of Medical Oncology (SEOM) and the Spanish Sarcoma Research Group (GEIS) and provide a multidisciplinary and updated consensus for the diagnosis and treatment of GIST patients. We strongly encourage that the managing of these patients should be performed within multidisciplinary teams in reference centers.

2023 GEIS Guidelines for gastrointestinal stromal tumors

Gastrointestinal stromal tumor (GIST) is the most common malignant neoplasm of mesenchymal origin. GIST spans a wide clinical spectrum that ranges from tumors with essentially no metastatic potential to malignant and life-threatening spread diseases. Gain-of-function mutations in KIT or PDGFRA receptor tyrosine kinases are the crucial drivers of most GISTs, responsible for tumor initiation and evolution throughout the entire course of the disease. The introduction of tyrosine kinase inhibitors targeting these receptors has substantially improved the outcomes in this formerly chemoresistant cancer. As of today, five agents hold regulatory approval for the treatment of GIST: imatinib, sunitinib, regorafenib, ripretinib, and avapritinib. This, in turn, represents a success for a rare neoplasm. During the past two decades, GIST has become a paradigmatic model in cancer for multidisciplinary work, given the disease-specific particularities regarding tumor biology and tumor evolution. Herein, we review currently available evidence for the management of GIST. This clinical practice guideline has been developed by a multidisciplinary expert panel (oncologist, pathologist, surgeon, molecular biologist, radiologist, and representative of patients' advocacy groups) from the Spanish Group for Sarcoma Research, and it is conceived to provide, from a critical perspective, the standard approach for diagnosis, treatment, and follow-up.

Cytoreductive surgery offers prognostic benefits in metastatic gastrointestinal stromal tumors with generalized progression following imatinib therapy: a single institute retrospective study

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Distant metastasis has been detected in approximately 50% of GIST patients at the first diagnosis. The surgical strategy for metastatic GIST with generalized progression (GP) after imatinib therapy remains unclear.

METHODS

We recruited 15 patients with imatinib-resistant metastatic GIST. They received cytoreductive surgery (CRS) for tumor rupture, intestinal obstruction and gastrointestinal bleeding. We collected clinical, pathological and prognostic data for analyses.

RESULTS

OS and PFS after R0/1 CRS were 56.88 ± 3.47 and 26.7 ± 4.12 months, respectively, when compared with 26 ± 5.35 and 5 ± 2.78 months after R2 CRS (P = 0.002 and P < 0.001, respectively). The OS of patients from the initiation of imatinib in the R0/1 group was 133.90 ± 15.40 months when compared with 59.80 ± 10.98 months in the R2 CRS group. There were two significant grade III complications after 15 operations (13.3%). No patient underwent reoperation. In addition, no perioperative death occurred.

CONCLUSIONS

R0/1 CRS is highly probable to provide prognostic benefits for patients with metastatic GIST who experience GP following imatinib treatment. An aggressive surgical strategy for achieving R0/1 CRS can be deemed safe. If applicable, R0/1 CRS should be carefully considered in imatinib-treated patients with GP metastatic GIST.

Prediction of the mitotic index and preoperative risk stratification of gastrointestinal stromal tumors with CT radiomic features

OBJECTIVE

The objective is to develop a mitotic prediction model and preoperative risk stratification nomogram for gastrointestinal stromal tumor (GIST) based on computed tomography (CT) radiomic features.

METHODS

A total of 267 GIST patients from 2009.07 to 2015.09 were retrospectively collected and randomly divided into (6:4) training cohort and validation cohort. The 2D-tumor region of interest was delineated from the portal-phase images on contrast-enhanced (CE)-CT, and radiomic features were extracted. Lasso regression method was used to select valuable features to establish a radiomic model for predicting mitotic index in GIST. Finally, the nomogram of preoperative risk stratification was constructed by combining the radiomic features and clinical risk factors.

RESULTS

Four radiomic features closely related to the level of mitosis were obtained, and a mitotic radiomic model was constructed. The area under the curve (AUC) of the radiomics signature model used to predict mitotic levels in training and validation cohorts (training cohort AUC = 0.752; 95% confidence interval [95%CI] 0.674-0.829; validation cohort AUC = 0.764; 95% CI 0.667-0.862). Finally, the preoperative risk stratification nomogram combining radiomic features was equivalent to the clinically recognized gold standard AUC (0.965 vs. 0.983) (p = 0.117). The Cox regression analysis found that the nomogram score was one of the independent risk factors for the long-term prognosis of the patients.

CONCLUSION

Preoperative CT radiomic features can effectively predict the level of mitosis in GIST, and combined with preoperative tumor size, accurate preoperative risk stratification can be performed to guide clinical decision-making and individualized treatment.

Unusual breast metastasis of gastrointestinal stromal tumor: A case report and literature review

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal tumors of gastrointestinal tract. The most common sites of metastases are the liver and the peritoneum, whereas breast metastases from GIST are extremely rare. We present a second case of GIST breast metastasis.

CASE SUMMARY

We found a case of breast metastasis from rectum GIST. A 55-year-old female patient presented with rectum tumor with multiply liver lesions and metastasis in the right breast. Abdominal-perineal extirpation of rectum was performed, histology and immunohistochemistry study showed GIST, mixed type with CD117 and DOG-1 positive staining. The patient was taking imatinib 400 mg for 22 mo with stable disease. Because of growth of the breast metastasis the treatment was changed twice: The dose of imatinib was doubled with further progression in the breast lesion and then the patient was receiving sunitinib for 26 mo with partial response in the right breast and stable disease in the liver lesions. The breast lesion increased and right breast resection was done – surgery on local progression, the liver metastases were stable. Histology and immunohistochemistry studies revealed GIST metastasis, CD 117 and DOG 1 positive with KIT exon 11 mutation. After surgery the patient resumed imatinib. Until now the patient has been taking imatinib 400 mg for 19 mo without progression, last follow up was in November 2022.

CONCLUSION

GISTs breast metastases are extremely rare, we described the second case. At the same time second primary tumors have been reported frequently in patients diagnosed with GISTs and breast cancer is one of the most common second primary tumors in patients with GISTs. That is why it is very important to distinguish primary from metastatic breast lesions. Surgery on local progression made it possible to resume less toxic treatment.

An unusual paraesophageal and diaphragmatic SDHA-deficient gastrointestinal stromal tumor (GIST) metastases case report

Background

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract and have diverse tumor biology. Succinate dehydrogenase (SDH)-deficient GIST, comprise less than 10% of all GIST, with mutational loss of the catalytic SDHA subunit being the most common subtype. Contrary to typical GISTs harboring inactivating mutations in KIT/PDGFRA, SDH-deficient GIST has varying biology and behavior, occurring at a younger age, often metastatic on presentation and frequently refractory to conventional tyrosine kinase inhibitors (TKI). Liver and peritoneum are their most common sites of metastases, and extra-abdominal spread to the diaphragm or mediastinum has not been previously described.

Case Description

Herein, we present a case of a 44-year-old female patient with a history of SDHA-deficient GISTs with multiple previous metastasectomies who presented with recurrence to the paraesophageal region and diaphragm which was identified upon routine positron emission tomography (PET) surveillance. Patient subsequently underwent a robotic assisted metastasectomy using a thoracic approach. Follow up was obtained 2 months following procedure and there was no evidence of recurrence.

Conclusions

SDHA-deficient GISTs have unique tumor biology and management of metastatic lesions remains an area of debate and discovery. Overall, this report highlights the need for comprehensive knowledge of the disease, a skilled surgical team, and multi-disciplinary involvement in order to optimize care and ensure favorable outcomes in this patient population.

Progress in the Treatment of Small Intestine Cancer

OPINION STATEMENT

Small intestine cancer is rare, accounting for approximately 3% of all gastrointestinal malignancies. The most common histological subtypes include adenocarcinoma, neuroendocrine tumours (NETs) and gastrointestinal stromal tumours (GISTs). In localised disease, surgery remains the mainstay of treatment and the best approach to improve survival. Current treatment for small intestine adenocarcinoma (SIA) is extrapolated from small studies and data from colorectal cancer (CRC). There is limited evidence to guide therapy in the adjuvant setting. However, there are small phase II studies in the advanced setting providing evidence for the role of chemotherapy and immunotherapy. There is also limited evidence assessing the efficacy of targeted therapies. Small intestine NETs are rare, with evidence for somatostatin analogue therapy, particularly in the low to intermediate-grade well-differentiated tumours. Poorly differentiated NETs are generally managed with chemotherapy but have worse outcomes compared with well-differentiated NETs. The management of small intestine GISTs is largely targeting KIT mutations with imatinib. Recent trials have provided evidence for effective therapies in imatinib-resistant tumours and the potential role of immunotherapy. The aim of this article was to review the evidence for the current management and recent advances in the management of small intestine adenocarcinoma, NETs and GISTs.

Advances of endoscopic and surgical management in gastrointestinal stromal tumors

As one of the most common mesenchymal malignancies in the digestive system, gastrointestinal stromal tumors (GISTs) occur throughout the alimentary tract with diversified oncological characteristics. With the advent of the tyrosine kinase inhibitor era, the treatment regimens of patients with GISTs have been revolutionized and GISTs have become the paradigm of multidisciplinary therapy. However, surgery resection remains recognized as the potentially curative management for the radical resection and provided with favorable oncological outcomes. The existing available surgery algorithms in clinical practice primarily incorporate open procedure, and endoscopic and laparoscopic surgery together with combined operation techniques. The performance of various surgery methods often refers to the consideration of risk evaluation of recurrence and metastases; the degree of disease progression; size, location, and growth pattern of tumor; general conditions of selected patients; and indications and safety profile of various techniques. In the present review, we summarize the fundamental principle of surgery of GISTs based on risk assessment as well as tumor size, location, and degree of progress with an emphasis on the indications, strengths, and limitations of current surgery techniques.

Five decades of sarcoma care at Memorial Sloan Kettering Cancer Center

Early studies of the management of soft tissue sarcoma at Memorial Sloan Kettering Cancer Center were influenced by development of robust prospective long-term databases. Increasing capacity for molecular diagnostics has identified a myriad of subtypes with definable natural history. Accurate identification of tissue-specific risk of recurrence and disease-specific survival have increasingly allowed selective use of surgery, radiation therapy, and target-specific cytotoxic and immune therapies.

Might Patients with Metastatic Gastrointestinal Stromal Tumors Benefit from Operative Management? A Population-Based Retrospective Study

Background

With respect to effect of surgery on the therapy of patients with metastatic gastrointestinal stromal tumors (mGISTs), still no consensus has been reached. This research designed to investigate the effect of surgical treatment on prognosis in patients with mGISTs.

Methods

The population-based study consisted of 6282 GIST patients diagnosed between 2001 and 2016, from the Surveillance, Epidemiology, and End Results (SEER) database registry. The Kaplan-Meier method and Cox model were employed for the exploration of the effect of surgery on overall survival (OS) and GIST-specific survival (GSS).

Results

In total, 6282 patients were diagnosed with GISTs, including 1238 (19.7%) mGIST patients and 5044 (80.3%) non-mGIST patients. Compared with the patients with non-mGISTs, metastatic patients assumed relatively lower proportion of surgical management (756 [61.1%] vs. 4666 [92.5%], P < 0.001). Based on unadjusted analysis, mGIST patients with operative management presented higher five years OS together with GSS in comparison with those without operative management (OS: 58.3% vs. 33.1%, P < 0.001; GSS: 61.6% vs. 36.7%, P < 0.001). Multivariable analysis found that no surgery was correlated to more than 2-fold increased death risk (OS, adjusted HR = 2.27, 95% CI: 1.90-2.71; GSS, adjusted HR = 2.42, 95% CI: 2.00-2.93).

Conclusion

Metastatic GIST patients could potentially benefit from operative management with improved GSS and OS.

Metastatic SDH-Deficient GIST Diagnosed during Pregnancy: Approach to a Complex Case

Gastrointestinal stromal tumors (GISTs) account for 1% of GI neoplasms in adults, and epidemiological data suggest an even lower occurrence in pregnant women. The majority of GISTs are caused by KIT and PDGFRA mutations. This is not the case in women of childbearing age. Some GISTs do not have a KIT/PDGFRA mutation and are classified as wild-type (WT) GISTs. WT-GIST includes many molecular subtypes including SDH deficiencies. In this paper, we present the first case report of a metastatic SDH-deficient GIST in a 23-year-old pregnant patient and the challenges encountered given her concurrent pregnancy. Our patient underwent a surgical tumor resection of her gastric GIST as well as a lymphadenectomy a week after induction of labor at 37 + 1 weeks. She received imatinib, sunitinib as well as regorafenib afterward. These drugs were discontinued because of disease progression despite treatment or after side effects were reported. Hence, she is currently under treatment with ripretinib. Her last FDG-PET showed a stable disease. This case highlights the complexity of GI malignancy care during pregnancy, and the presentation and management particularities of metastatic WT-GISTs. This case also emphasizes the need for a multidisciplinary approach and better clinical guidelines for offering optimal management to women in this specific context.

Gastrointestinal Stromal Tumors and the General Surgeon

Gastrointestinal stromal tumors (GISTs) are rare malignancies of the gastrointestinal tract but are the most common sarcoma. This review covers aspects of the care of patients with GIST relevant to surgeons. In particular, management of sub-2 cm GISTs, the utility of neoadjuvant and adjuvant therapy for primary GISTs, and indications for surgery in the setting of metastatic disease are discussed.

Role of Surgery in the Management of Liver Metastases From Gastrointestinal Stromal Tumors

Background

The clinical benefit of hepatectomy in patients with liver metastases from gastrointestinal stromal tumors (GIST) has not been well defined in this era of tyrosine kinase inhibitor (TKI). Our study aims to demonstrate the survival advantage of adding hepatectomy in patients with GIST liver metastases.

Methods

Information on patients with metastatic GIST treated or consulted between January 2006 and December 2018 was retrieved. Patients without extrahepatic metastases were included and classified into the surgical (S group) and non-surgical (NS group). Clinicopathological features were compared and their association with survival was assessed.

Results

A total of 119 patients were included in this retrospective analysis, 62 in the S group and 59 in the NS group. Comparison of clinicopathological features showed that a markedly higher proportion of patients in the S group had ≤3 hepatic lesions (79.0% vs. 29.8%, p<0.001). After a median follow-up duration of 56 months, patients in the S group had significantly better progression-free survival (PFS) and marginally improved overall survival (OS) than those in the NS group (3y PFS:86.2% vs. 64.6%, p=0.002; 5y OS: 91.5% vs. 78.3%, p=0.083). After propensity score matching, multivariate analysis identified hepatectomy as the only significant prognostic factor for PFS while age, hepatectomy and max tumor diameter were significant predictor for OS.

Conclusions

Addition of hepatectomy provided longer disease control in patients with metastatic GIST confined to the liver. Upfront hepatectomy followed by imatinib therapy is worthwhile trying in patients with single and easily removable lesions.

Radiotherapy in the Management of Gastrointestinal Stromal Tumors: A Systematic Review

Simple Summary

Gastrointestinal stromal tumors are considered to be insensitive to radiotherapy. However, with the development of radiation techniques and the accumulation of cases, some studies have indicated that radiotherapy could help achieve objective response in advanced or metastatic gastrointestinal stromal tumors. Therefore, it is necessary to conduct a systematic review to reassess the role of radiotherapy in gastrointestinal stromal tumors. The purpose of this study was to draw the attention of scholars and clinicians to radiotherapy and promote further research on radiotherapy in gastrointestinal stromal tumors.

Abstract

Gastrointestinal stromal tumors (GISTs) are considered insensitive to radiotherapy. However, a growing number of case reports and case series have shown that some lesions treated by radiotherapy achieved an objective response. The aim of the study was to perform a systematic review of all reported cases, case series, and clinical studies of GISTs treated with radiotherapy to reevaluate the role of radiotherapy in GISTs. A systematic search of the English-written literature was conducted using PubMed, Web of Science, and Embase databases. Overall, 41 articles describing 112 patients were retrieved. The included articles were of low to moderate quality. Bone was the most common site treated by radiotherapy, followed by the abdomen. In order to exclude the influence of effective tyrosine kinase inhibitors (TKIs), a subgroup analysis was conducted on whether and which TKIs were concurrently applied with radiotherapy. Results showed that radiotherapy alone or combined with resistant TKIs could help achieve objective response in selected patients with advanced or metastatic GISTs; however, survival benefits were not observed in the included studies. Pain was the most common symptom in symptomatic GISTs, followed by neurological dysfunction and bleeding. The symptom palliation rate was 78.6% after excluding the influence of effective TKIs. The adverse reactions were mainly graded 1–2. Radiotherapy was generally well-tolerated. Overall, radiotherapy may relieve symptoms for GIST patients with advanced or metastatic lesions and even help achieve objective response in selected patients without significantly reducing the quality of life. In addition to bone metastases, fixed abdominal lesions may be treated by radiotherapy. Publication bias and insufficient quality of included studies were the main limitations in this review. Further clinical studies are needed and justified.

The GIST of Advances in Treatment of Advanced Gastrointestinal Stromal Tumor

Gastrointestinal stromal tumor (GIST) is the most common malignant neoplasm of mesenchymal origin and a compelling clinical and biologic model for the rational development of molecularly targeted agents. This is because the majority of GISTs are driven by gain-of-function mutations in KIT or PDGFRA receptor tyrosine kinases. Specific GIST mutations circumscribe well-defined molecular subgroups that must be determined during the diagnostic work-up to guide clinical management, including therapeutic decisions. Surgery is the cornerstone treatment in localized disease and can also be clinically relevant in the metastatic setting. The correct combination and sequence of targeted agents and surgical procedures improves outcomes for patients with GIST and should be discussed individually within multidisciplinary expert teams. All currently approved agents for the treatment of GIST are based on orally available tyrosine kinase inhibitors targeting KIT and PDGFRA oncogenic activation. Although first-line imatinib achieves remarkable prolonged disease control, the benefit of subsequent lines of treatment is more modest. Novel therapeutic strategies focus on overcoming the heterogeneity of KIT or PDGFRA secondary mutations and providing more potent inhibition of specific challenging mutations. This article reviews the current understanding and treatment of GIST, with an emphasis on recent advances.

Gastrointestinal Stromal Tumor

Over the past 20 years, gastrointestinal stromal tumor (GIST) has evolved into an increasingly complex clinical entity with ever more challenges. While surgical resection is the gold standard, advancements in genetic testing, therapeutic options, immunotherapy, and management of metastatic disease necessitate a comprehensive, multimodal approach for these tumors. This chapter highlights the importance of genomic testing of GIST, the use of neoadjuvant and adjuvant therapy for localized disease, surgical principles for GIST, as well as current and new approaches for addressing metastatic disease.

Locoregional Treatments for Metastatic Gastrointestinal Stromal Tumor in British Columbia: A Retrospective Cohort Study from January 2008 to December 2017

Simple Summary

It is not known if surgery, radiation treatment (RT) or other types of locolregional treatment (LRT) may be beneficial for patients with metastatic gastrointestinal stromal tumor (mGIST) in addition to systemic treatment. Our study aims to address this question by analyzing a cohort of 127 mGIST patients in British Columbia over a decade (from January 2008 to December 2017). We showed that mGIST patients who underwent surgery and LRT seemed to have better survival when compared to patients who did not undergo surgery and LRT. However, this treatment strategy should only be considered in patients with limited volume metastatic disease or oligoprogression while the rest of the disease is well controlled with systemic treatment. In addition, RT can offer palliative benefits such as pain relief and bleeding control. Our study, consistent with other retrospective studies, supports LRT consideration in selected mGIST patients within a multidisciplinary setting. This approach is not considered as a “standard of care” due to lack of prospective clinical trials but may improve clinical outcome for some mGIST patients.

Abstract

Introduction: The role of surgery and non-surgical locoregional treatments (LRT) such as radiation therapy (RT) and local ablation techniques in patients with metastatic gastrointestinal stromal tumor (GIST) is unclear. This study examines LRT practice patterns in metastatic GIST and their clinical outcomes in British Columbia (BC). Methods: Patients diagnosed with either recurrent or de novo metastatic GIST from January 2008 to December 2017 were identified. Clinical characteristics and outcomes were analyzed in patients who underwent LRT, including surgical resection of the primary tumor or metastectomy, RT, or other local ablative procedures. Results: 127 patients were identified: 52 (41%) had de novo metastasis and 75 (59%) had recurrent metastasis. Median age was 67 (23–90 years), 58.2% were male, primary site was 33.1% stomach, 40.2% small intestine, 11% rectum/pelvis, and 15.7% others. 37 (29.1%) of patients received palliative surgery, the majority of which had either primary tumor removal only (43.3%) or both primary tumor removal and metastectomy (35.1%). A minority of patients underwent metastectomy only (21.6%). A total of 12 (9.5%) patients received palliative RT to metastatic sites only (58.3%) or primary tumors only (41.7%), mostly for symptomatic control (n = 9). A few patients (n = 3) received local ablation for liver metastatic deposits with 1 patient receiving microwave ablation (MWA) and 2 receiving radiofrequency ablation (RFA). Most patients (n = 120, 94.5%) received some type of systemic treatment. It is notable that prolonged progression free survival (PFS) was observed for the majority of patients who underwent surgery in the metastatic setting with a median PFS of 20.5 (95% confidence interval (CI): 14.29–40.74) months. In addition, significantly higher median overall survival (mOS) was observed in patients who underwent surgery (97.15 months; 95% CI: 77.7-not reached) and LRT (78.98 months; 95% CI: 65.58-not reached) versus no surgery (45.37 months; 95% CI: 38.7–64.69) and no LRT (45.27 months; 95% CI: 33.25–58.66). Almost all patients (8 out of 9) achieved symptomatic improvement after palliative RT. All 3 patients achieved partial response and 2 out of 3 patients had relatively durable responses of 1 year or more after local ablation. Discussion: This study is among the first to systematically examine the use of various LRT in metastatic GIST management. Integration of LRT with systemic treatments may potentially provide promising durable response and prolonged survival for highly selected metastatic GIST patients with low volume disease, limited progression and otherwise well controlled on systemic treatments. These observations, consistent with others, add to the growing evidence that supports the judicious use of LRT in combination with systemic treatments to further optimize the care of metastatic GIST patients.

Crizotinib in Sarcomatous Malignancies Harboring ALK Fusion With a Definitive Partner(s): Response and Efficacy

Sarcoma or sarcomatoid malignancies are a set of mesenchymal-origin malignancies with vast heterogeneity in clinical and molecular characteristics. Anaplastic lymphoma kinase (ALK) is a tyrosine kinase oncoprotein expressed by several tumors, including sarcomas. Crizotinib is an effective ALK inhibitor. In this review paper, we summarized findings from the literature regarding the use of crizotinib for the treatment of sarcoma and sarcomatoid malignancies harboring ALK fusions with definitive partners (with the given gene(s) name) from the years 2010 to 2021.One hundred and four articles were retrieved and after exclusion, 28 studies containing 33 patients were finally selected. All 33 patients were treated with crizotinib. Among the 33 cases, 19 were adult patients, 11 were pediatric patients, and 3 cases did not have data on age and/or gender. Most cases had a primary abdominal lesion (16/30), followed by thoracic (10/30), trunk (3/30), retroperitoneal (1/30), and one case of right medial thigh (case 7). Stage IV disease was reported in 76.7% (23/30) of patients. The objective response rate and disease control rate was 86.7% (26/30) and 96.7% (29/30), respectively, which were assessed on average of 8 weeks after crizotinib initiation. Rapid improvement of symptoms was observed within one to two weeks in some cases including patients with extensive diseases or poor performance. There was no difference in crizotinib response between pediatrics and adult cases. Crizotinib is effective; however, surgery remains the mainstay of therapy, with newer evidence showing concurrent crizotinib with surgery conferring long-term overall survival. However, we should still be cognizant of the heterogeneous landscape of crizotinib efficacy and its associated fatal adverse events.

Treatment of gastrointestinal stromal tumors: A single-center experience

OBJECTIVE:

Gastrointestinal stromal tumors are the most common mesenchymal tumors of the gastrointestinal tract. We aimed to examine the clinical characteristics and treatment outcomes of patients diagnosed with gastrointestinal stromal tumor (GIST) who were followed up and treated in our center.

METHODS:

This study retrospectively evaluated the clinical characteristics, disease stages, administered treatments, and treatment responses of 67 patients diagnosed with GIST who presented to our center between 2007 and 2015.

RESULTS:

Of the 67 patients included in our study, 24 (35.8%) were female and 43 (64.2%) were male. Median age at diagnosis was 54 years (23–86). Primary tumor localization was the stomach in 38.8% (n=26), small intestine in 46.2% (n=31), colorectal in 6% (n=4), and extra-gastrointestinal in 9% (n=6) of the patients. At diagnosis, 19 patients (28.4%) were at a metastatic stage. Fifty-seven patients (85.1%) underwent surgery. Thirty-three patients received one line, 20 patients received two lines, and 12 patients received three lines of treatment. The first-line treatment resulted in complete response in 12 patients (36.4%), partial response in 15 patients (45.5%), stable disease in 5 patients (15.2%), and progression in 1 patient (3%). Progression-free survival (PFS) was 36 months for the first-line treatment. The second-line treatment resulted in partial response in 7 patients (35%), stable disease in 12 patients (60%), and progression in 1 patient (5%). PFS was 12 months for the second-line treatment. The third-line treatment resulted in complete response in 1 patient (8.3%), partial response in 3 patients (25%), stable disease in 5 patients (41.7%), and progression in 3 patients (25%). PFS was 9 months for the third-line treatment. The fourth-line treatment resulted in stable disease in 4 patients (80%) and progression in 1 patient (20%). PFS was 4 months for the fourth-line treatment. Overall survival was 90 months for all patients.

CONCLUSION:

The use of tyrosine kinase inhibitors such as imatinib has a significant favorable effect on the prognosis in the treatment of GISTs, both in adjuvant therapy and in advanced stage disease.

Robotic-assisted Resection of a Diaphragmatic Metastasis of a Gastrointestinal Stromal Tumor

Gastrointestinal stromal tumors (GISTs) are relatively rare mesenchymal tumors. The treatment of these tumors has drastically changed based on molecular treatment methods, namely tyrosine kinase inhibitors, which have led to impressive survival benefits. While medical management has enhanced patient outcomes, surgery is still the standard of care for stable, completely resectable primary tumors or metastases that are >2 cm. This case presents the resection of a diaphragmatic metastasis of a tyrosine kinase inhibitor-controlled GIST in a 51-year-old male. The surgery was collaboratively approached from both the thoracic and abdominal cavities, utilizing the da Vinci robotic system. Prior data is limited regarding patient outcomes after robotic-assisted resection of GISTs. However, small case series have shown it to be a safe and effective surgical option. Our patient's quick recovery and return to normal function demonstrate the successful use of robotic-assisted surgery for GIST resection.

Prognostic Factors After Neoadjuvant Imatinib for Newly Diagnosed Primary Gastrointestinal Stromal Tumor

INTRODUCTION

Neoadjuvant imatinib (Neo-IM) therapy may facilitate R0 resection in primary gastrointestinal stromal tumors (GISTs) that are large or in difficult anatomic locations. While response to preoperative tyrosine kinase inhibitors is associated with better outcome in metastatic GIST, little is known about prognostic factors after Neo-IM in primary GIST.

STUDY DESIGN

Patients with primary GIST with or without synchronous metastases who underwent Neo-IM were retrospectively analyzed from a prospective maintained institutional database for Response Evaluation Criteria in Solid Tumors (RECIST), tumor viability, and mitotic rate. Overall survival (OS) was estimated by Kaplan-Meier and compared by log-rank test. Cox proportionate hazard models were used for univariate and multivariate analysis.

RESULTS

One hundred and fifty patients were treated for a median of 7.1 months (range 0.2-160). By RECIST, partial response, stable disease, and progressive disease were seen in 40%, 51%, and 9%, respectively. By pathologic analysis, ≤ 50% of the tumor was viable in 72%, and the mitotic rate was ≤ 5/50HPF in 74%. On multivariate analysis, RECIST response and tumor viability were not associated with OS, while post-treatment high mitotic rate (hazard ratio (HR) for death 5.3, CI 2.3-12.4), R2 margins (HR 6.0, CI 2.3-15.5), and adjuvant imatinib (HR 0.4, CI 0.2-0.9) were (p < 0.05). Five-year OS was 81 vs. 38% for low vs. high mitotic rate; 81, 59, and 39% for R0, R1, and R2 margins; and 75 vs 61% for adjuvant vs. no adjuvant imatinib therapy (p < 0.05).

CONCLUSIONS

In primary GIST undergoing Neo-IM therapy, progression was uncommon, but substantial down-sizing occurred in the minority. High tumor mitotic rate and incomplete resection following Neo-IM were associated with poor outcome, while adjuvant imatinib was associated with prolonged survival.

Surgical Management of Metastatic Gastrointestinal Stromal Tumors

OPINION STATEMENT

Treatment with the tyrosine kinase inhibitor (TKI), imatinib is the standard first-line treatment for metastatic gastrointestinal stromal tumors (GISTs). Unfortunately, acquired c-kit mutations cause secondary resistance to imatinib in a median of 18-24 months. Sunitinib and regorafenib are multi-kinase inhibitors that can be used as second-line or third-line therapy in imatinib-resistant or -intolerant GISTs, respectively. Ripretinib (a switch-control tyrosine kinase inhibitor) has recently been approved for fourth-line treatment in metastatic GIST. The TKI avapritinib has been approved for metastatic GIST harboring the imatinib-resistant PDGFRA exon 18 mutation. Although TKI therapies have revolutionized the treatment of metastatic GISTs, they cannot cure metastatic GISTs. Therefore, cytoreductive surgery is of considerable interest and has been accordingly investigated. Retrospective non-randomized studies demonstrated the feasibility and safety of continuous TKI therapy and surgical resection. Most studies demonstrate response to TKI therapy, completeness of resection, extent of disease, and surgical complexity as predictors of outcomes. Most TKIs can be stopped shortly before surgery and restarted shortly after. There is no known survival benefit from debulking operations or R2 resections and this should not be considered. However, debulking/palliative surgery may be necessary for patients with complications of hemorrhage, pain, or intestinal obstruction. SDH-deficient GISTs have an indolent natural history despite metastatic disease and may be another uncommon subgroup that would benefit from surgical debulking (R2 resection). At the time of operation, care should be taken to avoid tumor rupture. After surgical resection, patients should resume tyrosine kinase inhibitor (TKI) therapy as soon as possible and be monitored for disease progression. In all patients with metastatic GIST, the decision to pursue metastasectomy for GIST should be made in a multidisciplinary setting and be individualized according to patient age, comorbidities, functional status, symptoms, mutation status, extent of disease, completeness of resection, TKI response, and goals of the patient.

Surgical Management of Sarcoma Metastatic to Liver

Sarcomas are rare mesenchymal tumors with a propensity for hematogenous metastasis. Gastrointestinal stromal tumor (GIST) is the most common histologic subtype and the most common source of hepatic metastases. In the case of metastatic GIST, neoadjuvant imatinib can be used as a selection tool for the judicious application of surgery, where treatment-responsive patients who undergo resection to prevent the development of treatment-resistant clones have associated 10-year actuarial survival of 40%. Further advances for many of the non-GIST sarcoma subtypes will depend on the development of improved systemic therapies and evaluation of their activity in subtype or molecularly defined trials.

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.

The Landmark Series: Systemic Therapy for Resectable Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Complete resection is the only potentially curative treatment, although recurrence is common, occurring in approximately 40–50% of patients. The introduction of effective molecularly targeted therapies for GISTs has dramatically changed the clinical management paradigms for, and prognosis of, patients with intermediate- and high-risk GISTs, as well as those with locally advanced and metastatic disease. In this article, we review landmark studies that evaluated the use and efficacy of the tyrosine kinase inhibitors imatinib and sunitinib in the adjuvant and neoadjuvant settings for resectable primary and limited resectable metastatic GISTs.

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.

Preoperative imatinib treatment in patients with locally advanced and metastatic/recurrent gastrointestinal stromal tumors: A single-center analysis

The advent of imatinib mesylate (IM) has dramatically revolutionized the prognosis of advanced and metastatic/recurrent gastrointestinal stromal tumors (GISTs). The objective of this retrospective study is to investigate the safety and efficacy of combination of surgery following IM treatment in the management of advanced and metastatic/recurrent GISTs. We further explore the long-term clinical outcomes in these who underwent therapy of preoperative IM.Eligible patients with GISTs before the onset of the IM therapy and were periodically followed up in the outpatient clinic were included in this study. Detailed clinical and pathologic characteristics were obtained from the medical records of our institution. Univariate and multivariate regression analyses were performed to use for the evaluation of potential prognostic factors.A total of 51 patients were included in the study, of these patients, 36 patients underwent surgery and median duration of preoperative IM is 8.2months (range 3.5-85 months). Significant median tumor shrinkage rate was 29.27% (95% confidence interval 21.00%-34.00%) observed in these patients who responded to IM, and partial response and stable disease were achieved in 24 patients (47.06%) and 23 patients (45.10%), respectively, in light of the RECIST guideline (version 1.1). After the median follow-up of 43.70 months (range 14.2-131.1 months), 1- and 3-year overall survival (OS) were estimated to be 96.1% and 94.0%, respectively, and there was a significant improvement in OS for patients who received surgical intervention versus those who did not.Our study consolidates that patients were received preoperative IM therapy could shrink the size of tumors and facilitate organ-function preservation. The long-term analysis on this study supports that surgical intervention following IM therapy benefits for patients with primary advanced and recurrent or metastatic GISTs on long-term prognosis.

Role of Resection Following Focal Progression with Standard Doses of Imatinib in Patients with Advanced Gastrointestinal Stromal Tumors: Results of Propensity Score Analyses

BACKGROUND

There are limited data on the clinical benefits of adding surgical resection in patients with focally progressive gastrointestinal stromal tumor (GIST). This study aims to compare the clinical outcomes of resection plus imatinib dose escalation or maintenance (S group) with imatinib dose escalation alone (NS group) in patients with advanced GIST following focal progression (FP) with standard doses of imatinib.

MATERIALS AND METHODS

A total of 90 patients with advanced GISTs who experienced FP with standard doses of imatinib were included in this retrospective analysis. The primary endpoints were time to imatinib treatment failure (TTF) and overall survival (OS).

RESULTS

Compared with the NS group (n = 52), patients in the S group (n = 38) had a higher proportion of primary tumor site involvement and lower tumor burden at FP. With a median follow-up duration of 31.0 months, patients in the S group had significantly better TTF and OS than patients in the NS group (median TTF: 24.2 vs. 6.5 months, p < .01; median OS: 53.2 vs. 35.1 months, p = .009). Multivariate analysis showed that S group independently demonstrated better TTF (hazard ratio [HR], 0.29; p < .01) and OS (HR, 0.47; p = .01). Even after applying inverse probability of treatment-weighting adjustments, S group demonstrated significantly better TTF (HR, 0.36; p < .01) and OS (HR, 0.58; p = .049).

CONCLUSION

Our results suggested that resection following FP with standard doses of imatinib in patients with advanced GIST provides additional benefits over imatinib dose escalation alone.

IMPLICATIONS FOR PRACTICE

This is the first study to compare the clinical outcomes of resection plus imatinib dose escalation or maintenance (S group) with imatinib dose escalation alone (NS group) in patients with advanced gastrointestinal stromal tumor (GIST) following focal progression (FP) with standard doses of imatinib. These findings suggest that resection can be safely performed following FP, and the addition of surgical resection provides further clinical benefit over imatinib dose escalation alone. Based on these results, the authors recommend resection following FP in patients with advanced GIST provided that an experienced multidisciplinary team is involved in the patient's treatment.

Targeted therapy and personalized medicine in gastrointestinal stromal tumors: drug resistance, mechanisms, and treatment strategies

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Since the discovery that the KIT and PDGFRA receptor tyrosine kinases are the primary oncogenic drivers in the vast majority of GISTs, targeted therapy with tyrosine kinase inhibitors has been the mainstay of treatment for this disease. Using molecular profiling of tumor specimens, researchers also discovered that KIT and PDGFRA mutations are non-random and occur in specific regions of the receptors, and furthermore, that particular genotypes predicted response or resistance to targeted therapy. Imatinib, the first tyrosine kinase inhibitor used to treat GIST, remains the first-line therapy in advanced GIST and the only therapy confirmed through clinical trials in the adjuvant or neoadjuvant setting for resectable disease. Resistance to imatinib is well described and is either primary or secondary. Primary resistance is associated with specific tumor genotypes, so genotyping of individual patient tumors helps guide decision-making into whether to offer imatinib and at what dose. Secondary resistance occurs due to the acquisition of secondary mutations during therapy. Currently, the main strategy to combat imatinib resistance is to switch to another tyrosine kinase inhibitor, because imatinib-resistant GIST is usually still oncogenically addicted to KIT/PDGFRA signaling. Surgery can also be used to combat resistant disease in select settings. Unfortunately, progression-free and overall survival remains dismal for patients who develop imatinib-resistant disease, and further research into alternative strategies is still needed.

Role for targeted resection in the multidisciplinary treatment of metastatic gastrointestinal stromal tumor

The management of advanced gastrointestinal stromal tumors (GISTs) has evolved in the modern era due to the discovery of c-kit mutations and the development of tyrosine kinase inhibitors (TKIs). Until the advent of TKIs such as imatinib, the median survival reported for patients with advanced GIST was 19 months. Although surgery is the treatment of choice for resectable primary GIST, its role in cases of recurrence and metastasis remains to be unclear. This review outlines the potential beneficial role of repeat surgical resection in the multidisciplinary treatment of advanced GIST in the era of TKIs.

Gastrointestinal Stromal Tumors of the Stomach and Esophagus

Gastrointestinal stromal tumors (GISTs) arise anywhere along the gastrointestinal tract, most commonly as a result of c-kit or PDGFRA proto-oncogene mutations. Surgical resection is an important component of treatment. However, molecular profiling of GISTs has provided many insights into adjuvant and neoadjuvant therapy options. Imatinib, the most frequently studied medical therapy, has been shown in numerous studies to provide benefit to patients in both the neoadjuvant and adjuvant setting. Interval imaging is an important component of the treatment of GISTs and national surveillance recommendations should be followed.

Intra-abdominal desmoid tumors mimicking gastrointestinal stromal tumors - 8 cases: A case report

BACKGROUND

Intra-abdominal desmoid tumors (DTs) can mimic recurrence or progression of gastrointestinal stromal tumors (GISTs). Differential diagnosis is important to avoid unnecessary or inappropriate treatment.

CASE SUMMARY

All 8 patients experienced surgical resection of GIST, and median time to diagnosis of DT was 1.8 years after surgical resection. All sites of DT were in the peritoneum around the surgical sites of GIST. The following clinical suspicion coupled with radiological findings contributed to the suspicion of intra-abdominal DTs: (1) Occurrence of a new single lesion in the peritoneum around the surgical sites of GIST; (2) uncontrolled lesion with imatinib while other lesions being controlled with imatinib; (3) well-defined ovoid shaped lesion with delayed or mild enhancement and absence of necrosis, hemorrhage, and cystic change on computed tomography; and (4) a lesion showing mild or no hypermetabolic activity on 18fluorodeoxyglucose-positron emission tomography, contrary to initially hyperactive lesion of GIST. All DTs were surgically removed except for one unresectable DT and only one DT recurred at another site of peritoneum, which was also surgically removed.

CONCLUSION

Intra-abdominal DT should be a differential diagnosis for a new single lesion in patients with GIST.

Indications for the surgical resection of stage IV disease

Tumor biology and careful patient selection weigh heavily in determining the appropriate role of surgical resection in stage IV melanoma. Historically, surgical resection for highly selected patients with metastatic melanoma was the only treatment modality associated with improved long-term survival and the ability to provide palliation. With the new age of effective systemic therapies, the treatment of metastatic melanoma has become more intricate and future work is needed to better define the role for surgery within the current treatment paradigm.

Preoperative tyrosine kinase inhibitors risks bowel anastomotic healing in patients with advanced primary and recurrent/metastatic gastrointestinal stromal tumors--- A rose has its thorns

BACKGROUND

The combination of tyrosine kinase inhibitors (TKIs) and surgery has created a paradigm shift for advanced primary and metastatic gastrointestinal stromal tumors (GISTs). However, the associated surgical morbidity rate is reportedly high, which we hypothesized is attributable to the adverse effects of the previous use of TKIs on bowel anastomosis healing.

METHODS

A total of 613 GIST patients with (n = 108) and without (n = 505) preoperative TKI treatment were enrolled. Propensity score matching compared the surgical morbidities and mortalities between the two cohorts. An animal model was used to elucidate the relevant mechanism.

RESULTS

After propensity score matching, the incidence and severity of surgical complications were higher in patients with preoperative TKIs than in those without (34% vs 10%, p < 0.0001; grades 3-5, 16% vs 2%, p < 0.0001). Specifically, the incidence of bowel anastomosis leakage was increased in those with versus those without preoperative TKI (18% vs 6%, p = 0.032). A constellation of mucosal shedding, shortening of villus height and crypt depth, and disarrayed epithelial lining of the bowel was observed with preoperative TKI treatment. The animal model showed that bowel anastomosis healing was weakened by imatinib through the downregulation of Col1A1, Col3A1, and MMPs.

CONCLUSIONS

Impaired bowel anastomosis healing was responsible for the extraordinarily high surgical morbidity rate of patients with GIST after TKI treatment. The mechanism involved altered tissue microarchitecture and dysregulated Col1A1, Col3A1, and MMP expressions.

Surgery for Gastrointestinal Stromal Tumors: State of the Art of Laparoscopic Resection and Surgery for M1 Tumors

BACKGROUND

The principles of surgery for primary gastrointestinal stromal tumor (GIST) are resection with clear margins without lymphadenectomy, thus enabling organ-preserving resection in many cases. Tumor rupture needs to be avoided, because it entails peritoneal sarcomatosis. Given these preconditions, there is a rationale for laparoscopic resection of primary GIST. In metastatic GIST, surgery cannot achieve cure, but constitutes an important cornerstone of treatment. Resection can be performed either for residual lesions in responding patients, for focally progressive lesions, or as palliative measure in generalized progression.

METHODS

Selective literature review.

RESULTS

There is ample evidence on laparoscopic resection of gastric GIST, but none from randomized trials. The studies show favorable perioperative outcomes and suggest adequate oncological results; however, a direct comparison to open resection is difficult. For surgery in M1 stages, survival outcomes are better for resection in generalized response than in focal progression. Perioperative morbidity is acceptable. Surgery in generalized progression does not prolong survival and bears relevant morbidity risks.

CONCLUSION

Laparoscopy seems an adequate surgical approach for primary gastric GIST, as long as the surgical principles relevant for this entity are respected. For other tumor sites, there is no sufficient evidence available. In M1 stages, selected patients may benefit from surgery. Survival differences between resection at different stages probably mirror the biology of the disease rather than the effect of the timing of the operation.

Clinicopathological and Molecular Characterization of Metastatic Gastrointestinal Stromal Tumors with Prolonged Benefit to Frontline Imatinib

BACKGROUND

Oncogenic KIT/PDGFRA signaling inhibition with imatinib achieves disease control in most patients with advanced/metastatic gastrointestinal stromal tumor (GIST), but resistance eventually develops after 20-24 months. Notably, a small subset of these patients obtain durable benefit from imatinib therapy.

METHODS

We analyzed clinical, pathological, and molecular characteristics and long-term outcomes in patients with metastatic GIST treated with continuous daily dosing of frontline imatinib in a cohort of patients benefiting for ≥5 years. A control group was obtained from the national Spanish Group for Sarcoma Research database and used as comparator.

RESULTS

Sixty-four imatinib long-term responders (LTRs) and 70 control cases were identified. Compared with controls, LTRs at baseline had better performance status (PS) 0-1 (100% vs. 81%), lower mitotic count (median, 8 vs. 15), and tumor burden (number of metastases, 3 vs. 7). KIT exon 11 was the only region found mutated in LTRs. LTRs achieved 34% complete responses and a median progression-free survival of 11 years, compared with 4% and 2 years, respectively, in the control cohort. Prognostic factors that independently predicted long-term benefit with imatinib were PS, number of metastases prior to imatinib, and response to imatinib. Fifteen LTR patients developed new side effects attributable to imatinib after ≥5 years of continuous treatment. No resistance mutations were found in metastatic samples from three patients progressing on imatinib.

CONCLUSION

GISTs in LTRs are a distinctive entity with less aggressive behavior and marked sensitivity to KIT inhibition. Patients reaching 5 or more years on imatinib have a higher chance of remaining progression free over time.

IMPLICATIONS FOR PRACTICE

This work demonstrates that clinical and inherent tumor characteristics define a subset of patients with gastrointestinal stromal tumor (GIST) with increased likelihood to achieve durable response to first-line imatinib therapy. Patients reaching ≥5 years on imatinib have a greater chance of remaining progression free over time, although the disease is unlikely to be cured. Imatinib is well tolerated for >5 years, and emergent toxicities are overall manageable. Resistance to imatinib emerging in patients with GISTs after long-term imatinib treatment does not involve polyclonal expansion of KIT secondary mutations.

Perspectives on the evolving state of the art management of gastrointestinal stromal tumours

Gastrointestinal stromal tumours (GISTs) represent a very exciting tumour entity for the medical oncologist. There has been extensive clinical and preclinical research dissecting the natural behaviour, molecular landscape and therapeutic responsiveness of this rare mesenchymal tumour. Various molecular subtypes of GIST have a differing prognostic and predictive relevance in the state of the art management of the disease. Emerging mature clinical trial data gathered over the last one and half decade provided substantial molecular profiling information in understanding the success and eventual failure of treatment. In our review of the most relevant literature we aim to guide the clinician in tailoring neoadjuvant, adjuvant and palliative treatment of GIST alongside the different, now well established molecular subgroups of GISTs.

Identification of preoperative factors associated with outcomes following surgical management of intra-abdominal recurrent or metastatic GIST following neoadjuvant tyrosine kinase inhibitor therapy

BACKGROUND

The role of surgical resection in the treatment of patients with metastatic/recurrent gastrointestinal stromal tumors (GIST) is unclear. The aim of this study was to identify preoperative factors associated with oncologic outcomes for recurrent/metastatic GIST after tyrosine kinase inhibitor (TKI) therapy.

METHODS

We identified 107 patients with metastatic or recurrent GIST treated with TKIs and surgical resection (2002-2012). Patients that underwent palliative or incomplete resection were excluded. Complete resection was achieved in 87 patients which comprise the analytic cohort. Univariate and multivariate analyses were conducted to identify risk factors for GIST-specific survival (DSS) and time-to-recurrence (TTR).

RESULTS

At a median follow-up of 51 months (91 months for survivors), median DSS was 74 months and TTR was 21 months. By univariate analysis, unifocal disease, duration of TKI < 365 days, and no evidence of radiographic progression were associated with improved TTR and DSS. Multivariate Cox regression demonstrated that evidence of radiographic progression was associated with shorter DSS (HR 2.53, 95%CI = 1.27-5.06, P = 0.008) and increased risk of recurrence (HR 3.33, 95%CI = 1.91-5.82, P < 0.001).

CONCLUSIONS

Patients with unifocal disease and radiographic evidence of response to TKI therapy may achieve improved oncologic outcomes when complete surgical resection is achieved following treatment with TKI.

Prediction of morbidity following cytoreductive surgery for metastatic gastrointestinal stromal tumour in patients on tyrosine kinase inhibitor therapy

BACKGROUND

Although cytoreductive surgery has been shown to be beneficial in carefully selected patients with metastatic gastrointestinal stromal tumours (GISTs) treated with tyrosine kinase inhibitors (TKIs), factors predictive of postoperative morbidity have not been investigated previously.

METHODS

A surgical complexity score for GIST metastasectomy (GM-SCS) composed of patient-related and surgical factors was assigned retrospectively to patients with metastatic GIST treated with TKI therapy and surgery at two institutions between 2002 and 2014. The ability of clinicopathological factors and GM-SCS to predict postoperative morbidity was assessed by means of a multivariable logistic regression model. Postoperative complications were categorized using the Clavien-Dindo classification.

RESULTS

Some 400 operations on 323 patients with metastatic GIST on TKIs were included. Complications were observed following 110 operations (27·5 per cent) including 70 major complications (grade III-V) (17·5 per cent of 400 operations). Patients were divided into low (5 points or less; 100 patients, 25·0 per cent), intermediate (6-9 points; 191, 47·8 per cent) and high (at least 10 points; 109, 27·3 per cent) complexity scoring groups based on the GM-SCS. An intermediate (odds ratio (OR) 2·88; P = 0·008) and high (OR 5·40; P < 0·001) GM-SCS were independent predictors of overall complications, whereas only a high GM-SCS was independently predictive of a major complication (OR 3·65; P = 0·018). Metastatic mitotic index was also an independent predictor of overall complications (OR 2·55; P = 0·047). GM-SCS did not predict progression-free or overall survival.

CONCLUSION

A gastrointestinal stromal tumour metastastectomy surgical complexity score can predict morbidity, which may help in preoperative risk stratification and optimal treatment planning.

Surgery for metastatic gastrointestinal stromal tumor: to whom and how to?

Although imatinib is a standard treatment for metastatic or recurrent gastrointestinal stromal tumors (GISTs), acquired c-kit mutations reportedly cause secondary resistance to imatinib. Sunitinib is a tyrosine kinase inhibitor (TKI) that can be used as second-line therapy in imatinib-resistant or -intolerant GISTs. For sunitinib-resistant or -intolerant GISTs, regorafenib is a standard third-line treatment. Although TKI therapies have revolutionized the treatment of recurrent or metastatic GISTs, they cannot cure GISTs. Therefore, in the era of TKIs, role of cytoreductive surgery for recurrent or metastatic GISTs has been discussed. Retrospective studies of treatment strategies with front-line surgery prior to imatinib have shown that initial cytoreduction confers no benefit in cases of advanced or recurrent GIST, and administering imatinib is the principle treatment. Most retrospective studies report cytoreductive surgery to be feasible in patients with metastatic GIST whose disease is stable or responsive to imatinib. Cytoreductive surgery may be indicated in limited disease progression refractory to imatinib when complete resection is possible, but case selection is critical. Cytoreductive surgery for metastatic GIST treated with sunitinib seems less feasible because of high rates of incomplete resections and complications. The role of cytoreductive surgery for metastatic GISTs would be difficult to establish in a prospective study; individualized treatments need to be carefully designed based on c-kit and platelet-derived growth factor receptor alpha (PDGFRA) mutations and other factors.

Recent advances in managing gastrointestinal stromal tumor

Constitutive activating mutations in KIT and platelet-derived growth factor receptor α ( PDGFRα) are heavily involved in the pathobiology of gastrointestinal stromal tumors (GISTs). This disease has served as an effective "proof-of-concept" model for targeting gain-of-function kinase mutations in cancer. This review discusses the current standard of care in terms of pharmacotherapy in the management of localized and metastatic GISTs.

Surgical treatment of gastrointestinal stromal tumors of the stomach: current status and future perspective

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract, with the majority found in the stomach. Surgical resection of the primary gastric GISTs with complete resection margin has been the forefront of curative treatment. The indications for surgical resection are usually related to symptomatic gastric GISTs at presentation. Primary gastric GISTs resection performed conventionally through an open surgery can now be frequently achieved by minimal invasive surgery with similar oncological outcome. Surgeon's selection of the type of surgical techniques such as open, laparoscopic and endoscopic resections depends on the site, size and local invasion of gastric GISTs to the adjacent organ. Similarly those factors dictate the extent of gastric resections in the form of wedge, partial or total gastrectomy. All these inherent tumor factors (size and mitotic index), patient factors (older age, male) and surgical factors (incomplete resection margin, tumor rupture or spillage) play an important role in stratifying the malignant potential risk of primary gastric GISTs and their chances of recurrence. The understanding of gene mutation driving the growth of GISTs and the discovery of tyrosine kinase inhibitors (TKIs) has altered the surgical management of advanced and metastatic GISTs. Multi-modal therapy incorporating the surgical resection of GISTs and utilizing the molecular targeted therapy in the adjuvant, neoadjuvant and palliative settings can offer optimal personalized outcome and prolong patient's overall survival (OS).