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.

Comparison of two doses of imatinib for the treatment of unresectable or metastatic gastrointestinal stromal tumors: a meta-analysis of 1,640 patients

PURPOSE

The Gastrointestinal Stromal Tumor Meta-Analysis Group (MetaGIST) project aims to additionally explore the data of the two large, randomized, cooperative-group studies comparing two doses of imatinib (400 mg daily v twice daily) in 1,640 patients with advanced GIST.

METHODS

End points were progression-free survival (PFS) and overall survival (OS). Investigated cofactors included age, sex, performance status (PS), primary tumor site, time from diagnosis, prior therapies, baseline biology, and KIT/PDGFRalpha mutations for a subset of 772 patients. Univariate and multivariate models were used for the analysis.

RESULTS

At a median follow-up of 45 months, a small but significant PFS advantage was documented for the high-dose arm. OS was identical in the two arms. The multivariate prognostic models included the following adverse factors: male sex, poor PS, and high baseline neutrophils counts (PFS and OS); low hemoglobin and GIST from small bowel origin (PFS); and advanced age, large tumor size, low albumin level, and prior chemotherapy (OS). In patients analyzed for mutations, patients with wild type, patients with KIT exon 9 mutations, and patients with other mutations had worse prognoses than patients with KIT exon 11 mutations for both end points. The mutation status was the only predictive factor for the PFS benefit attributed to high-dose treatment that resulted in significantly longer PFS (and higher objective response rate) for patients with KIT exon 9 mutations.

CONCLUSION

This analysis confirms a small PFS advantage of high-dose imatinib, essentially among patients with KIT exon 9 mutations, but no OS advantage.

Clonal evolution of resistance to imatinib in patients with metastatic gastrointestinal stromal tumors

PURPOSE

Resistance to imatinib mesylate is emerging as a clinical challenge in patients with metastatic gastrointestinal stromal tumors (GIST). Novel patterns of progression have been noted in a number of these patients. The objective of this study was to correlate molecular and radiologic patterns of imitinib-refractory disease with existing conventional criteria for disease progression.

EXPERIMENTAL DESIGN

Patients with metastatic GIST treated with imatinib were followed with serial computed tomography/magnetic resonance imaging and [(18)F]fluoro-2-deoxy-d-glucose positron emission tomography. Where feasible, biopsies were done to document disease progression.

RESULTS

A total of 89 patients were followed for a median of 43 months. Forty-eight patients developed progressive disease. A unique "resistant clonal nodule" pattern (defined as a new enhancing nodular focus enclosed within a preexisting tumor mass) was seen in 23 of 48 patients and was thought to represent emergence of clones resistant to imatinib. Nodules were demonstrable a median of 5 months (range, 0-13 months) before objective progression defined by tumor size criteria and were the first sign of progression in 18 of 23 patients. Median survival among patients whose first progression was nodular was 35.1 months, compared with 44.6 months for patients whose first progression met Southwest Oncology Group criteria (P = 0.31). Comparative tumor biopsies were done in 10 patients at baseline and from progressing nodules. Genotypic analyses of KIT and PDGFRA kinases were done, revealing new activating kinase mutations in 80% (8 of 10) of these patients.

CONCLUSION

The resistant clonal nodule is a unique pattern of disease progression seen in patients with GISTs after an initial response to imatinib and reflects the emergence of imatinib-resistant clones. Conventional tumor measurements (Southwest Oncology Group/Response Evaluation Criteria in Solid Tumors) do not detect this subtle finding. A new enhancing nodule growing within a preexisting tumor mass should be classified as a new lesion and be regarded, at least, as partial progression of GIST.

Issues in Imaging-Guided Tumor Ablation in Children Versus Adults

OBJECTIVE

Despite the growing use of percutaneous imaging-guided tumor ablation in adults, few reports describe its use in children except for osteoid osteoma. Our objective is to describe how tumor ablation in children and adults may differ, both to facilitate dialogue on pediatric tumor ablation and to increase awareness and use of this valuable technique.

CONCLUSION

There are numerous indications for which various ablative techniques may be safe and effective for treatment of pediatric tumors. Nonetheless, important differences between the pediatric and adult populations warrant consideration.

Management of metastatic gastrointestinal stromal tumour in the Glivec era: a practical case-based approach

Gastrointestinal stromal tumour is now recognized as a distinct pathological malignancy and has received much attention over the last few years. Despite almost universal resistance to chemotherapy, a novel therapy, Imatinib, which targets the KIT receptor, has changed the natural history of this disease. We have audited the first 26 consecutive patients with gastrointestinal stromal tumour treated over 4 years at a single institution. A practical guide to the management of common toxicities and drug resistance is reported with a review of the published reports. Many of the strategies used are likely to be widely applicable to the use of targeted therapies in other malignancies.

Imatinib and gastrointestinal stromal tumors: Where do we go from here?

Imatinib has tremendously changed the treatment of gastrointestinal stromal tumor (GIST). Research is currently focusing on its optimal use and the mechanisms of resistance that may emerge. A multidisciplinary approach including medical oncologists, surgeons, radiologists, and pathologists is crucial for the optimal management of these patients. Moreover, imatinib treatment in GIST represents an extraordinary model to expand our knowledge on the molecular mechanisms that are basic to the effects of molecularly targeted therapies. This review summarizes the existing knowledge of the imatinib treatment in GIST and describes directions for further development.