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

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.

Salvage Hepatectomy for Giant GIST Liver Metastases Unresponsive to Systemic Therapy-Case Report

Therapeutic decision-making for advanced GIST liver metastases is challenging due to limited clinical evidence. This case study aims to demonstrate the survival benefit of resection in non-responsive cases. A 40-year-old male presented with abdominal pain, weight loss, altered general status, massive hepatomegaly, and intermittent melaena. He was diagnosed with stage IV GIST with the primary tumor in the ileal loop and multiple gigantic synchronous bilobar liver metastases. Despite 31 months of tyrosine-kinase inhibitor therapy post-primary tumor resection, the disease remained unresponsive. The patient was admitted to our tertiary center with significant hepatomegaly. A two-stage debulking liver resection was performed after a multidisciplinary team decision. The first operation debulked the left hemiliver through a non-anatomical ultrasound-guided resection of segments 2, 3, and 4. The second operation (7 weeks later) debulked the right hemiliver through a right posterior sectionectomy involving segments 5 and 8. Despite receiving a second line of tyrosine-kinase inhibitor therapy after surgery, the disease progressed both within and outside the liver. However, the patient survived for 55 months, with a postoperative survival benefit of 25 months. In conclusion, this case emphasizes the significant survival benefit achieved through a complex two-stage debulking liver resection for giant liver metastases, even in cases where systemic therapy fails.

Update of epidemiology, survival and initial treatment in patients with gastrointestinal stromal tumour in the USA: a retrospective study based on SEER database

OBJECTIVES

An updated epidemiological analysis of gastrointestinal stromal tumour (GIST), the change of cancer-specific survival (CSS) and patterns of initial treatment are of interest.

DESIGN

A retrospective study using data from the Surveillance, Epidemiology and End Results (SEER) database.

SETTING AND PARTICIPANTS

A total of 5625 patients with GIST diagnosed between 2010 and 2019 were identified.

PRIMARY OUTCOME MEASURES

Age-standardised incidence rate (ASIR) and annual prevalence rate were calculated. SEER combined stage, period CSS rate and initial treatment were summarised. All the data were calculated by SEER*Stat software.

RESULTS

From 2010 to 2019, the ASIR of GIST increased from 0.79 to 1.02 per 100 000 person-years, with an increase of 2.4% annually. The increase was across age and sex subgroups. The prevalence trend was similar with the ASIR trend in each subgroup. The stage distributions were similar between different age groups, but varied among different primary tumour sites. More importantly, a stage shift from regional stage to localized stage at diagnosis was found, which may result in the improvement of CSS over years. Overall, the 5-year CSS rate of GIST was approximately 81.3%. Even for metastatic GIST, the rate exceeded 50%. Surgery was the most common treatment regimen for GIST, followed by surgery and systemic treatment. Whereas approximately 7.0% patients were undertreated, which was more pronounced among patients with distant and unknown stages.

CONCLUSIONS

The findings of this study suggest an improving early detection of GIST and an improving ability of accurate staging. Though most patients are effectively treated and perform good survivals, approximate 7.0% patients may be undertreated.

Interruption of imatinib in advanced gastrointestinal stromal tumor after prolonged imatinib maintenance in the absence of gross tumor lesions

BACKGROUND

Current guidelines recommend indefinite imatinib treatment for advanced gastrointestinal stromal tumor (GIST) patients. Imatinib-refractory progression-free survival (PFS) and overall survival were previously reported not to differ between GIST patients who interrupted imatinib and those who did not.

METHODS

Clinical outcomes of 77 consecutive patients with recurrent or metastatic GIST who interrupted imatinib treatment after maintaining years of imatinib treatment in the absence of gross tumor lesions were retrospectively analyzed. Associations between clinical factors and progression-free survival (PFS) following imatinib interruption were analyzed.

RESULTS

The median time from the absence of gross tumor lesions to imatinib interruption was 61.5 months. Since imatinib interruption, the median PFS was 19.6 months, and 4 patients (26.3%) remained progression-free for longer than 5 years. Among the patients who had progressive disease following the interruption, imatinib re-introduction led to an 88.6% objective response rate and a 100% disease control rate. Complete removal of the initial gross tumor lesion(s) and complete removal of the residual gross tumor lesion(s) by local treatment (vs. no local treatment or residual lesions after local treatment) were independently associated with favorable PFS.

CONCLUSION

Interruption of imatinib following prolonged maintenance in the absence of gross tumor lesions led to disease progression in the majority of cases. However, re-introduction of imatinib resulted in effective tumor control. Unmaintained remission seems to be possible in some patients with metastatic or recurrent GIST after a prolonged remission with imatinib if there is complete removal of any gross tumor lesions.

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.

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.

Molecular Portrait of GISTs Associated With Clinicopathological Features: A Retrospective Study With Molecular Analysis by a Custom 9-Gene Targeted Next-Generation Sequencing Panel

Objectives: The study aims to investigate genetic characterization of molecular targets and clinicopathological features with gastrointestinal stromal tumors based on targeted next-generation sequencing.

Materials and Methods: We selected 106 patients with GISTs from Sir Run Run Shaw Hospital between July 2019 and March 2021. FFPE samples and paired blood samples were obtained from these patients who underwent excision of the tumor. A customized targeted-NGS panel of nine GIST-associated genes was designed to detect variants in the coding regions and the splicing sites of these genes.

Results: In total, 106 patients with a GIST were included in the study which presented with various molecular driver alterations in this study. KIT mutations occurred most often in GISTs (94/106, 95.92%), followed by point mutations in PDGFRA. KIT or PDGFRA mutations were detected to be mutually exclusive in the GIST. A total of eight patients with wide-type KIT/PDGFRA were characterized as WT-GISTs, according to clinical diagnosis which included six quadruple-WT GISTs, 1 BRAF-mutant, and 1 NF1-mutant GIST. In KIT exon 11, the most common mutation type was the codon Mutation (in-frame deletion or indels), whereas the missense mutation was the dominant type in KIT exon 13 and KIT exon 17. All variations in KIT exon 11 observed in this study were concentrated at a certain position of codon 550 to codon 576. Mutation in KIT exon 9 was mostly located at codon 502–503. Two germline pathogenic mutations were detected: NF1-R681* and KRAS-T58I. NF1-L591P was a germline mutation to be identified for the first time and is not recorded in the database. The frequency of driving mutations differed between the primary anatomical site in the GIST (p = 0.0206). KIT exon 11 mutants had a lower proliferation index of Ki67 (68.66%,≤5%), while 50.00% of KIT exon 9 mutants had the Ki67 status greater than 10%.

Conclusion: The occurrence and development of a GIST is driven by different molecular variations. Resistance to TKIs arises mainly with resistance mutations in KIT or PDGFRA when they are the primary drivers. Targeted NGS can simultaneously and efficiently detect nine GIST-related gene mutations and provide reference for clinicians’ individualized diagnosis and treatment. Our results have important implications for clinical management.

Neuroendocrine Tumor with Metachronous Gastrointestinal Stromal Tumor in a Patient: A Case Report

Neuroendocrine tumors (NETs) that arise from neuroendocrine cells can develop in most organs; however, it is rarely found in the duodenal papilla. Conversely, gastrointestinal stromal tumors (GISTs), which are mostly asymptomatic and detected incidentally, are usually found in the stomach and very rarely occur metachronously with NETs. A 42-year-old female with no specific underlying disease underwent gastroscopy due to epigastric pain. Biopsy of enlarged major and minor duodenal papilla confirmed the diagnosis of a NET. Endoscopic papillectomy of the major and minor papillae was performed. Multiple duodenal and jejunal submucosal nodules were seen on biliary CT performed at the 30 months follow-up. Pylorus-preserving pancreaticoduodenectomy was performed due to the suspicion of multiple recurrent NETs and muscularis propria involvement on endoscopic ultrasound. Surgical specimen biopsy confirmed the diagnosis of multiple duodenal and jejunal GIST lesions and a metastatic NET in the duodenal lymph node. We report a rare case of a GIST detected in the duodenum during follow-up after the diagnosis and papillectomy of duodenal papilla NET.

Primary Tumor Resection Improves Survival in Patients With Metastatic Gastrointestinal Stromal Tumors: A Preliminary Population-Based Analysis

Background: Surgery has been the primary treatment in patients with localized gastrointestinal stromal tumors (GISTs) for many decades, whereas it remains controversial regarding the efficacy of primary tumor resection for metastatic GISTs treated with chemotherapy, and likewise it is unclear who would benefit from the surgical resection.

Methods: GISTs patients with distant metastases were identified from the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2016. Cox proportional hazards regression models were used to identify prognostic factors of overall survival (OS) and cancer-specific survival (CSS). Kaplan-Meier analyses and log-rank tests were conducted to assess the effectiveness of surgery on survival.

Results: In total, of 455 patients with metastatic GISTs, 235 patients (51.6%) underwent primary tumor resection and 220 patients (48.4%) did not. Median survival of patients in resection group was 72 (95% CI: 62.90–81.10) months vs. 40 (95% CI: 29.53–50.47) months for those in non-resection group (p < 0.001). Similarly, surgery in conjunction with chemotherapy led to a favorable impact on survival than chemotherapy alone (OS: 72 vs. 40 months, p < 0.001; CSS: 74 vs. 44 months, p < 0.001). Multivariable analysis showed that both OS (HR: 0.581, 95% CI: 0.386–0.874, p = 0.009) and CSS (HR: 0.663, 95% CI: 0.439–0.912, p = 0.042] were dramatically improved in patients with surgical removal of primary site, as well as primary tumor size between 5 and 10 cm, while increasing age was predictive of poorer survival. Stratified analysis revealed that patients with tumor locations in the stomach demonstrated a prolonged survival after surgery, with no significant differential surgical effect between the stomach and small intestine.

Conclusions: Our study preliminarily suggests that carefully selected patients with metastatic GISTs might prolong survival after treatment of surgery, especially those with a primary tumor between 5 and 10 cm and a tumor located in the stomach.

Thermal ablation versus hepatic resection for the treatment of liver metastases from gastrointestinal stromal tumors: a retrospective study

Objective: The study aimed to compare effectiveness and safety of thermal ablation and hepatic resection in patients with liver metastases of gastrointestinal stromal tumors (GISTs).Method: A total of 55 patients (27 in the ablation group and 28 in the surgery group) with liver metastases were included. Overall survival (OS) and progression-free survival (PFS) were assessed with Kaplan-Meier's survival estimate curves. Univariate and multivariate regression analyses were carried out to identify potential prognostic factors.Results: The median OS was 102.0 months in the ablation group and 117.0 months in the surgery group (p = .875). The 1-, 3- and 5-year OS rates were 100%, 88.9% and 74.1% in the ablation group and 92.8%, 82.1% and 78.6% in the surgery group, respectively. The 1-, 3- and 5-year PFS rates were 48.1%, 25.9% and 18.5% in the ablation group and 67.8%, 64.3% and 64.3% in the surgery group, respectively. Multivariate analysis showed that preoperative tyrosine kinase inhibitor (TKI) treatment (progressive disease, PD) (HR, 13.985; 95% CI, 1.791-109.187; p = .012) was the only significant independent prognostic factor for OS. Tumor number (HR, 1.318; 95% CI, 1.021-1.702; p = .034) was identified as an independent predictor for PFS in multivariate analysis. There were fewer postoperative complications (18.5% vs. 78.6%, p = .001) and shorter lengths of hospital stay (8.0 vs. 16.5 days, p = .001) in the ablation group.Conclusion: Compared with resection, thermal ablation offered comparable OS for liver metastases of GISTs. Furthermore, thermal ablation had the advantages of fewer complications and shorter lengths of hospital stay.

Resection Combined with TKI Therapy for Resectable Liver Metastases of Gastrointestinal Stromal Tumours: Results from Three National Centres in China

OBJECTIVE

To investigate the differences in the efficacy of hepatic resection combined with tyrosine kinase inhibitor (TKI) therapy versus TKI therapy alone and the timing of the TKI therapy and hepatic resection for resectable liver metastases from gastrointestinal stromal tumours (GISTs).

METHODS

This was a retrospective review of 43 patients confirmed to have resectable liver metastases from GISTs who received TKI treatment alone or the therapy model of hepatic resection combined with TKIs and were admitted to one of 3 institutions between January 2006 and December 2017.

RESULTS

For all liver metastases patients, the 1-, 3- and 5-year survival rates were 97.67%, 88.98% and 66.46%, respectively. The median overall survival (OS) was 85 months. Patients who underwent hepatic resection combined with TKI therapy had a significantly better OS and a trend towards improved progression-free survival (PFS) than patients who received TKIs alone (P = 0.001, mOS 102 months versus 51 months; P = 0.077, mPFS 42 months versus 30 months). Hepatic resection combined with TKI therapy was the only prognostic factor for long-term survival in the multivariate analysis (HR = 0.198, 95% CI 0.048-0.813, P = 0.025). Compared with patients who underwent hepatic resection combined with postoperative TKIs only, patients who underwent hepatic resection combined with perioperative TKIs had a significantly better PFS (P = 0.032, mPFS 29 months versus 19 months) but did not have a significantly better OS (P = 0.662, mOS 92 months versus 102 months). Resection combined with perioperative TKI therapy was the only prognostic factor for PFS in the multivariate analysis (HR = 0.295, 95% CI 0.101-0.862, P = 0.026).

CONCLUSIONS

For patients with resectable liver metastases, hepatic resection combined with TKI therapy was more beneficial in terms of improving prognosis than TKIs alone. In terms of the timing of TKI therapy and hepatic resection, resection combined with perioperative TKIs may prolong PFS more than resection combined with postoperative TKIs only.

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.

The Role of Surgical Resection Following Tyrosine Kinase Inhibitors Treatment in Patients with Advanced Gastrointestinal Stromal Tumors: A Systematic Review and Meta-analysis

Background The benefit of surgical resection for advanced gastrointestinal stromal tumors (GISTs) following tyrosine kinase inhibitors (TKIs) treatment was still under debate. The present meta-analysis was designed to assess the value of surgical resection for the prognosis of patients with metastatic, recurrence and unresectable GISTs. Methods A systematic search of PubMed Central, PubMed, EMBASE and the Cochrane Library database was performed. Relevant studies of the role of surgery in advanced GISTs published before 1 May 2019 were identified. The quality of studies was assessed by the Newcastle-Ottawa Quality Assessment Scale. The progression-free survival (PFS) and overall survival (OS) were assessed through software Stata 15.0. Results A total of 6 retrospective studies including 655 patients were analyzed. The pooled result revealed that surgical resection group was associated with better PFS (HR = 2.08; 95% CI: 1.58 to 2.76; P<0.001) and better OS (HR = 2.13; 95% CI: 1.59 to 2.85; P<0.001) compared with TKIs treatment alone group. Conclusions Surgical resection following TKIs treatment could significantly improve the prognosis of patients with advanced GISTs.

Cytoreductive Surgery for Metastatic Gastrointestinal Stromal Tumors Treated With Tyrosine Kinase Inhibitors: A 2-institutional Analysis

OBJECTIVE

To refine treatment recommendations for patients with metastatic gastrointestinal stromal tumors (GISTs) treated with tyrosine kinase inhibitors (TKIs) and surgery.

BACKGROUND

Early reports suggested that patients with metastatic GIST responding to TKIs treated with surgery may have favorable outcomes. However, identification of prognostic factors was limited by small cohorts.

METHODS

Progression-free survival (PFS) and overall survival (OS) from time of surgery and from start of initial TKI was determined. Multivariate analysis was conducted on all patients undergoing GIST metastasectomy between 2001 and 2014 at 2 institutions.

RESULTS

We performed 400 operations on 323 patients with metastatic GIST on TKIs. Radiographic response at time of surgery was classified as responsive disease (RD, n = 64, 16%), stable disease (SD, n = 100, 25%), unifocal progressive disease (UPD, n = 132, 33%), and multifocal progressive disease (MPD, n = 104, 26%). For patients on imatinib before surgery, radiographic response was predictive of PFS from time of surgery (RD 36 months, SD 30 months, UPD 11 months, MPD 6 months; P < 0.001) and from imatinib initiation (RD 71 months, SD 51 months, UPD 47 months, MPD 33 months; P < 0.001). Radiographic response was predictive of OS from time of surgery (RD not reached, SD 110 months, UPD 59 months, MPD 24 months; P < 0.001), and from imatinib initiation (RD not reached, SD 144 months, UPD 105 months, MPD 66 months; P = 0.005). Radiographic response was not predictive of PFS/OS for patients on sunitinib. Metastatic mitotic index ≥5/50 HPF, MPD, and R2 resection were prognostic of worse PFS/OS; primary mutation was not.

CONCLUSIONS

Surgery in metastatic GIST patients in the absence of MPD on imatinib is associated with outcomes at least comparable with second-line sunitinib and may be considered in select patients.

Radiofrequency ablation versus resection for resectable liver metastases of gastrointestinal stromal tumours: Results from three national centres in China

OBJECTIVE

The aim of the present study was to compare outcomes after curative intent radiofrequency ablation and resection in patients with resectable liver metastases of Gastrointestinal Stromal Tumours (GISTs) after pre-operative tyrosine kinase inhibitor (TKI) treatment.

METHODS

We retrospectively analysed data from 25 patients diagnosed with resectable liver metastases from GISTs who received pre-operative TKI treatment, who received radiofrequency ablation or resection and post-operative TKI treatment, and who were admitted to 3 institutions from January 2009 to December 2017.

RESULTS

Ten patients (10/25, 40.00%) underwent RFA combined with post-operative TKI treatment, and 15 (15/25, 60.00%) patients were treated with hepatic resection combined with post-operative TKI treatment. There were fewer post-operative complications (10.00% vs. 53.33%, P = 0.04) and shorter length of stay (4 vs. 9 days, P = 0.00) in the RFA group. After a median follow-up of 26 months, the 1-, 3-, and 5-year survival rates were 100.00%, 75.00%, 55.00%, respectively. The RFA group had a lower median PFS (P = 0.007, mPFS: 9 months versus 29 months), but overall survival was not influenced by the treatment modality compared with the resection group (P = 0.413, mOS: 47 months versus not reached).Hepatic resection combined with post-operative TKI treatment was the only prognostic factor for PFS in univariate analysis (HR = 0.071, 95% CI: 0.007-0.759, P = 0.029).

CONCLUSIONS

For patients with resectable liver metastases from GISTs after receiving pre-operative TKI treatment, compared with resection, ablation seemed to be associated with shorter progression-free survival, but RFA offered comparable overall survival, and the post- procedure morbidity and lengths of stay were significantly lower. With complete ablation of the targeted tumours, our results suggest that RFA is an acceptable option in selected patients.

Long-term adjuvant imatinib treatment for a patient who underwent complete resection of a localized recurrent gastrointestinal stromal tumor after preoperative imatinib treatment: A case report

RATIONALE

The efficiency and tolerance of long-term adjuvant imatinib treatment for patient who underwent complete resection of a localized recurrent gastrointestinal stromal tumor (GIST) was unknown.

PATIENT CONCERNS

A 45-year-old man underwent complete resection of an intestinal GIST in August 2001. Four years later, a giant (11 × 8 × 6 cm) recurrent GIST located in the retroperitoneum was detected.

DIAGNOSIS

The recurrent tumor was positive for CD117 by immunohistochemistry.

INTERVENTIONS

The recurrent tumor was completely resected after 4 months of effective imatinib treatment (400 mg/day), and the patient continued imatinib treatment postoperatively. In June 2011, imatinib treatment was stopped for 3 weeks because of hepatitis B infection, and resumed with a reduced dose level of 300 mg/day when liver function recovered. In March 2017, imatinib treatment was interrupted again for 12 days because the patient underwent cholecystectomy.

OUTCOMES

In December 2017, a computed tomography scan showed no signs of tumor recurrence. To date, the patient has been under adjuvant imatinib treatment for >12 years without severe side effects. The plasma concentration of imatinib (detected in February 2018) was trough concentration (Cmin) 1015.7 ng/mL and peak concentration (Cmax) 1550.5 ng/mL.

LESSONS

This case report highlights the active role of long-term (>12 years) imatinib treatment after complete resection of localized recurrent GIST.

Long-term survival outcome with tyrosine kinase inhibitors and surgical intervention in patients with metastatic or recurrent gastrointestinal stromal tumors: A 14-year, single-center experience

The long‐term effects of tyrosine kinase inhibitors (TKIs), including imatinib, and surgical intervention on advanced gastrointestinal stromal tumor (GIST) were evaluated. All 379 patients had metastatic or recurrent GIST and started 400 mg/d imatinib at the Asan Medical Center in periods 1 and 2 [2001‐2007 (33.2%) and 2008‐2014 (66.8%), respectively]. Men constituted 60.4%; median patient age and tumor size at the initiation of imatinib were 58.6 (14.6‐85.5) years and 51 (0‐324) mm, respectively, without differences between periods except for older age and less preimatinib surgery in period 2. Response and disease control rates with imatinib in measurable GIST were 63.1% and 94.3%, respectively, without differences between periods. More patients in period 2 underwent surgical resection for TKI‐responsive diseases within the first 2 years (24.9%, P = 0.006). With a median follow‐up of 6.1 years (2.5‐16.0) in survivors, median progression‐free survival (PFS) was 5.4 years [95% confidence interval (CI), 4.0‐6.9]. Subsequent sunitinib (P = 0.066) and regorafenib (P = 0.003) were more commonly administered in period 2. Median overall survival (OS) was 8.8 years (95% CI, 7.8‐9.7). PFS with imatinib (P = 0.002) and OS (P = 0.019) were significantly longer in period 2. Young age, smaller tumor size at the initiation of imatinib, KIT exon 11 mutation, surgical intervention, and period 2 were favorable factors for PFS and OS. Patients with advanced GIST showed better prognosis with the optimal use of imatinib, along with active surgical intervention and more common use of subsequent TKIs in period 2.

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.

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.

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

Objective

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

Materials and Methods

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

Results

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

Conclusion

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

Imatinib dose escalation versus sunitinib as a second-line treatment against advanced gastrointestinal stromal tumors: A nationwide population-based cohort study

BACKGROUND

Although treatment with imatinib in advanced gastrointestinal stromal tumor (GIST) patients has led to significant clinical benefits, the disease will eventually progress due to imatinib resistance. Treatment options after failure of first-line imatinib include imatinib dose escalation or shifting to sunitinib. However, there is no large-scale study to compare the efficacy difference between these two treatment strategies or the role of surgery.

RESULTS

This study recruited 521 advanced GIST patients including 246, 125, and 150 placed in groups 1, 2, and 3, respectively. Groups 1 and 2 had significantly longer overall survival (OS) as compared with the group 3 (median 37.5 months versus 16.0 months; p < 0.0001). After adjusting for confounding variables, groups 1 and 2 had longer OS than group 3. A favorable survival trend was seen with surgery, although this benefit disappeared after adjusting for confounding factors.

MATERIALS AND METHODS

We conducted a nationwide population-based cohort study using data from the Taiwan National Health Insurance Research Database from July 2004 to December 2010. Advanced GIST patients who no longer responded to first-line imatinib were stratified into three groups: imatinib dose escalation (group 1); imatinib dose escalation and a shift to sunitinib (group 2); a direct shift to sunitinib (group 3). The therapeutic success of the three treatment regimens and the effect of surgery were evaluated by overall survival.

CONCLUSIONS

For advanced GIST patients who failed first-line imatinib treatment, imatinib dose escalation confers significantly longer OS compared to a direct switch to sunitinib. Surgery does not provide survival benefits.

Hepatectomy for liver metastasis from gastrointestinal stromal tumor in the era of imatinib mesylate: a case series study

The prognosis of metastatic gastrointestinal stromal tumor (GIST) has improved since the introduction of imatinib mesylate; however, acquired resistance has been reported, so alternative treatment option is needed. We evaluated the efficacy of hepatectomy for metastatic GIST. Six patients with liver metastases from GIST underwent hepatectomy. Four were treated with imatinib mesylate before hepatectomy, and all the patients were treated with imatinib mesylate after hepatectomy. Patients were followed-up for a mean duration of 113.5 months after hepatectomy. Complete resection was accomplished in four patients, with incomplete resection performed in the remaining two patients due to peritoneal dissemination. One patient with incomplete resection died 10 months after surgery. One patient with complete resection has survived without disease progression since initial hepatectomy. The remaining four patients with progressive disease during imatinib mesylate treatment developed tumor recurrence and three of them underwent a second hepatectomy. These three patients underwent complete resection during repeat surgery. In total, three patients died during the follow-up period, all of whom had tumors of small intestine origin. Primary tumor site (small intestine vs. others) was identified as a risk factor of mortality (P = 0.02). Although not statistically significant, there was a trend toward better outcomes in patients with exon 11 mutations. Surgical resection for metastatic GIST was shown to be effective and needed to achieve a better prognosis. Repeat hepatectomy demonstrated efficacy in selected patients. Hepatectomy should be considered based on tumor characteristics such as primary tumor site and c-KIT mutation status.

Partial response to imatinib treatment in a patient with unresectable gastrointestinal stromal tumor: A case report and mini literature review

The aim of the present study was to evaluate the efficacy and safety of imatinib mesylate in unresectable gastrointestinal stromal tumor (GIST) and to discuss its therapeutic regimen. A patient with unresectable GIST is described, and several key clinical studies are reviewed, including the clinical trials B2222 and S0033, which contain recently reported results of the long-term clinical outcome of imatinib in patients with unresectable or metastatic GIST. The recent results of the two studies demonstrate the long-term efficacy and safety of imatinib for unresectable or metastatic GIST. A positive response to imatinib treatment was observed in the present patient, which is consistent with the data of the B2222 and S0033 trials. However, further long-term, large-scale, multicenter and controlled trials are required to determine the relative efficacy of combining imatinib agents with surgical procedures or administering imatinib alone.

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

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

Neoadjuvant imatinib: longer the better, need to modify risk stratification for adjuvant imatinib

BACKGROUND

Multimodality treatment of gastrointestinal stromal tumor (GIST) with surgery and adjuvant imatinib mesylate (IM), along with an emerging role for neoadjuvant IM prior to evaluation for resectability has resulted in high survival rates.

METHODS

We conducted a retrospective analysis of prospectively collected data of patients who underwent surgery for GIST, prior to or followed by IM therapy. A total of 112 patients underwent surgery between January 2009 and March 2015 at our centre. This included 27 patients with upfront resectable disease, 76 patients with locally advanced GIST who received neoadjuvant IM followed by surgery and 9 patients with metastatic disease who had excellent response to IM and were taken for surgery.

RESULTS

The primary tumor in the non metastatic patients was in the stomach (53%), duodenum (16%), rectum (12%), jejunum (11%), ileum (7%), and others (2%). Median duration of neoadjuvant IM was 5 months with 4 patients showing disease progression during neoadjuvant IM. Ninety-three percent of all patients had R0 resections, while 7% had R+ resections. The estimated 3- and 5-year DFS in non-metastatic patients was 86.1% and 67% respectively with a 3- and 5-year median OS of 95.4% and 91.7% respectively. Five-year PFS and OS for the metastatic patients was 88.8% and 100% respectively. Lack of adjuvant IM was the only factor related to inferior PFS and OS.

CONCLUSIONS

Longer duration of neoadjuvant IM should be considered in locally advanced GIST prior to surgery and resection may be considered in responding metastatic patients.

Combined Therapy of Gastrointestinal Stromal Tumors

Radical surgery is the mainstay of therapy for primary resectable, localized gastrointestinal stromal tumors (GIST). Nevertheless, approximately 40% to 50% of patients with potentially curative resections develop recurrent or metastatic disease. The introduction of imatinib mesylate has revolutionized the therapy of advanced (inoperable and/or metastatic) GIST and has become the standard of care in treatment of patients with advanced GIST. This article discusses the proper selection of candidates for adjuvant and neoadjuvant treatment in locally advanced GIST, exploring the available evidence behind the combination of preoperative imatinib and surgery.

Indications for surgery in advanced/metastatic GIST

Gastrointestinal stromal tumours (GISTs) are a relatively rare entity and often present as a locally advanced tumour or with metastatic disease. Complete surgical resection is the only means of cure in localised disease; however, imatinib therapy has greatly advanced the management of GIST and is established as both an adjunct to surgery in high-risk cases and as principle therapy in metastatic disease. Surgery in advanced GIST has undergone a renaissance in recent years with the potential for a combined treatment approach with either neoadjuvant imatinib in locally advanced primary disease or as an adjunct to imatinib in those with metastases or recurrent disease. Neoadjuvant imatinib can render a locally advanced primary GIST resectable, allow less invasive procedures or promote preservation of function, especially if the tumour is located in an anatomically difficult position. The role of surgery in metastatic or recurrent disease is more controversial and case selection is critical. The potential benefit is difficult to quantify, although surgery may have a limited favourable impact on progression-free survival and overall survival for those patients whose disease is responding to imatinib or those with limited focal progression. Patients with imatinib resistant disease should not be offered surgery unless as an emergency where palliative intervention may be justified.

Role of metastasectomy for recurrent/metastatic gastrointestinal stromal tumors based on an analysis of the Kinki GIST registry

PURPOSE

To define the role of surgery for metastatic/recurrent lesions after resection of primary gastrointestinal stromal tumors (GISTs).

METHODS

Based on data obtained from the Kinki GIST registry, patients with recurrence or metastasis were divided into a surgical treatment group (ST group), comprised those treated with surgery in addition to tyrosine kinase inhibitor (TKI) therapy; and a drug treatment group (DT group), comprised those treated with TKI therapy alone. We compared the baseline characteristics and survival outcomes of the groups.

RESULTS

Metastasis or recurrence developed in 93 of the 737 patients with GISTs treated between 2003 and 2007, 50 (53.8 %) of whom were assigned to the ST group and 43 (46.2 %) to the DT group. In the ST group, the 5-year overall survival rate was significantly higher for patients who underwent R0/R1 resection than for those who underwent R2 resection (82.2 vs. 47.0 %, p = 0.018). Survival time after recurrence was correlated with the duration of total TKI therapy in both the ST and DT groups (r = 0.766 and r = 0.932, respectively, p < 0.001).

CONCLUSIONS

Continuous TKI therapy appears to be important primarily for the prognostic improvement of patients with recurrent/metastatic GISTs. R0/R1 resection may have benefits when combined with TKI therapy for patients with stable disease or disease responsive to TKI therapy, less than four metastatic lesions, and lesions <100 mm in total.

Present and future role of surgery in metastatic gastrointestinal malignancies

PURPOSE OF REVIEW

Metastases from gastrointestinal malignancies are systemic or abdominal disseminations of cancer cells. From a biological perspective surgical resections are questionable but case series show that for some tumour types, surgery influences survival outcome. This review focuses on management and indications for surgery in recent literature of these metastatic gastrointestinal malignancies.

RECENT FINDINGS

A few gastrointestinal malignancies have emerged to be candidates for surgery in case of metastatic disease. Surgery can be considered in selected cases with liver metastases or abdominal dissemination of colorectal cancer, metastases from gastrointestinal stromal tumours or neuroendocrine tumours. On the contrary, recent publications do not support surgery for metastatic disease of any other gastrointestinal origin. The literature has ample examples of small series and anecdotal cases of successful surgical interventions for most tumour types but no new evidence has been presented to support broader indications for surgery.

SUMMARY

The evidence base for surgery of different metastatic gastrointestinal malignancies is unchanged. There are some clarifications when to perform surgery and the timing of surgery in regard to combined treatments. No new tumour types are added to potential candidates for surgery.

Role of surgery in patients with focally progressive gastrointestinal stromal tumors resistant to imatinib

The benefits of surgery for focally progressive gastrointestinal stromal tumor (GIST) during imatinib therapy are still in discussion. The aim of this study was to compare the outcomes of surgical resection of progressive lesions following tyrosine kinase inhibitor (TKI) therapy (S group) or TKI therapy alone (NS group) in GIST patients. We retrospectively investigated 57 patients with focally progressive GIST during imatinib therapy who were treated in Zhongshan hospital, Fudan University. Progression-free survival (PFS) and overall survival (OS) in the S group were significantly longer than those in the NS group. Among S group, the patients with R0 resection showed longer PFS than R2 resection; however, no difference was found between these two groups. Moreover, PFS and OS were not different in the NS-S group compared with S group. On multivariate analysis, surgery is an independent prognostic factor for longer PFS and OS. Our study supports the decision of treating GIST patients who were focally resistant to imatinib with surgery resection based on its benefit.

[Intra-abdominal and retroperitoneal sarcomas]

Sarcomas are a heterogeneous group of rare tumors that originate from mesenchymal tissue. Radical R0 resection is the only curative option, which is especially challenging in retroperitoneal or intra-abdominal sarcomas. This article describes the current data on optimal interdisciplinary and primarily surgical therapy of visceral sarcomas. Surgical resection of retroperitoneal sarcomas must be performed according to the principle of radical compartmental resection, i.e. with complete excision of the mass along with en bloc visceral resection of adjacent organs and tissues covering the tumor, which also contains any not obviously infiltrated neighboring organs. The main objective is R0 resection without opening the tumor capsule in the primary operation because the best long-term results can be achieved with this approach.

Moving towards best practice when using inverse probability of treatment weighting (IPTW) using the propensity score to estimate causal treatment effects in observational studies

The propensity score is defined as a subject's probability of treatment selection, conditional on observed baseline covariates. Weighting subjects by the inverse probability of treatment received creates a synthetic sample in which treatment assignment is independent of measured baseline covariates. Inverse probability of treatment weighting (IPTW) using the propensity score allows one to obtain unbiased estimates of average treatment effects. However, these estimates are only valid if there are no residual systematic differences in observed baseline characteristics between treated and control subjects in the sample weighted by the estimated inverse probability of treatment. We report on a systematic literature review, in which we found that the use of IPTW has increased rapidly in recent years, but that in the most recent year, a majority of studies did not formally examine whether weighting balanced measured covariates between treatment groups. We then proceed to describe a suite of quantitative and qualitative methods that allow one to assess whether measured baseline covariates are balanced between treatment groups in the weighted sample. The quantitative methods use the weighted standardized difference to compare means, prevalences, higher‐order moments, and interactions. The qualitative methods employ graphical methods to compare the distribution of continuous baseline covariates between treated and control subjects in the weighted sample. Finally, we illustrate the application of these methods in an empirical case study. We propose a formal set of balance diagnostics that contribute towards an evolving concept of ‘best practice’ when using IPTW to estimate causal treatment effects using observational data. © 2015 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.

Treatment and Prognoses in Patients With Primary Gastrointestinal Stromal Tumors ≥10 cm: A Single-Institution Experience in China

Data on treatments and specific outcomes of primary gastrointestinal stromal tumors (GISTs) ≥10  cm are limited. We here report the treatments and survival outcomes concerning a subgroup of primary giant GISTs. Data of 83 consecutive patients with primary GISTs ≥10  cm in a single institution were retrospectively collected. Fifty-eight patients underwent surgery before imatinib mesylate (IM) treatment (Group A), 10 underwent surgical resection following IM therapy (Group B), whereas 15 patients took IM as drug therapy alone (Group C). The baseline clinical characteristics were similar among the 3 groups. However, a lower proportion in Group A had metastatic disease at the time of diagnosis or surgery compared with Groups B and C (8.6% vs 40.0% vs 40.0%, P < 0.05). The median follow-up duration was 21.5 months. No statistically significant differences were observed on progression-free survival (PFS) among the groups. However, patients in Group B showed significantly better overall survival (OS) compared with those in Group C (P = 0.044). Multivariate analysis showed that patients treated with adjuvant IM were associated with better PFS (hazard ratio [HR] 3.01; 95% confidence interval [CI] 1.13-7.97; P = 0.027) and OS (HR 29.11; 95% CI 3.32-125.36; P = 0.004). The subgroup with mitotic count >10/50 high-power fields (HPF) showed worse PFS (HR 3.50; 95% CI 1.19-10.25; P = 0.022) and OS (HR 20.04; 95% CI 1.67-143.79; P = 0.018) than that of mitotic count ≤5/50 HPF. Clinical treatment patterns for primary giant GISTs are different, and the outcomes of different interventions vary. The optimal treatments for these subgroup of patients still require further long-term investigation. Moreover, mitotic count and adjuvant IM are closely associated with PFS and OS in giant GISTs.