Gastrointestinal stromal tumor: a method for optimizing the timing of CT scans in the follow-up of cancer patients

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.

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.

[Surgical and interdisciplinary treatment of gastrointestinal stromal tumors]

Gastrointestinal stromal tumors (GISTs) are the most frequent potentially malignant mesenchymal tumors of the gastrointestinal tract. The treatment of GISTs has been revolutionized since imatinib and other tyrosine kinase inhibitors were introduced for the treatment of GISTs, which inhibit the tyrosine kinases c‑KIT and platelet-derived growth factor receptor (PDGFR) alpha. Even after the introduction of this targeted treatment GISTs can only be cured by surgical resection. With interdisciplinary multimodal treatment the prognosis of metastasized GIST can now be further improved by surgical resection of the primary tumor and the metastases, potentially leading to a cure. Neoadjuvant therapy can reduce the extent of surgical resection and hereby enable organ preservation and reduce surgical morbidity. To evaluate molecular and clinical predictors and to offer an optimal therapeutic plan, patients with GISTs and certainly patients with advanced GISTs should be evaluated by interdisciplinary sarcoma boards.

Imaging surveillance of gastrointestinal stromal tumour: current recommendation by National Comprehensive Cancer Network and European Society of Medical Oncology-European Reference Network for rare adult solid cancers

Imaging plays an active role in the surveillance of gastrointestinal stromal tumours (GISTs). Risk stratification schemes, based on size, mitotic count, and anatomical site of origin of the GIST, help in planning preoperative and postoperative imaging strategies especially in determining the frequency and duration of surveillance; however, there is no clear consensus on the optimal imaging strategies in patients with GISTs who are completely cured by surgery and patients who are at risk of recurrence. In addition, current surveillance protocols depend on the resectability of the primary tumour and presence of metastatic disease. The objective of this article is to provide a comprehensive review of the role of the different imaging methods for surveillance of GISTs, focusing on the guidelines recommended by National Comprehensive Cancer Network and European Society of Medical Oncology - European Network for Rare adult solid Cancers, and to propose practical guidelines for surveillance of GISTs for various risk categories.

Local and Metastatic Relapse Features in Patients After a Primary Soft Tissue Sarcoma: Advocating for a Better-Tailored Follow-Up

Background: No consensus exists on how to follow patients after complete remission of a primary Soft Tissue Sarcoma (STS). Studying relapse features could help tailor guidelines for follow-up.

Patients and Methods: Patients in complete remission after initial management of a localized STS at Institut Bergonié who presented a first local and/or metastatic relapse between January 1995 and July 2015 were eligible. Characteristics of relapse diagnosis were retrospectively collected.

Results: 359 patients met inclusion criteria. 197 and 187 patients presented a local relapse and a metastatic relapse, respectively. In group 1 (limbs/trunk wall) and 2 (trunk/gynecological/other location), local relapse was diagnosed on clinical symptoms in 89 and 44% of cases, first detected by the patient himself in 68.5 and 34% of cases, and outside a planned visit in 67 and 36% of cases, respectively. In patients with metastatic relapse, diagnosis was made during a planned visit in 63% of cases, and by imaging in 62% of cases. Median survival after relapse was not different whether the first local relapse was diagnosed clinically or by imaging (44 [95%CI: 28–69.8] vs. 57 months [95%CI: 33.9–84.5], p = 0.35) but was longer if diagnosis of metastatic relapse was made on planned chest-CT scan rather than chest X-ray (58 [95%CI: 35.5–103.9] vs. 25 months [95%CI: 16.5–32.6], p < 0.05).

Conclusion: Patient's education for regular clinical examination can be recommended for follow-up of local relapses after a primary STS of the limbs or superficial trunk. Modeling studies aiming at better understanding and predicting tumor biology to improve tailoring STS patients' follow-up are warranted.

Asian consensus guidelines for gastrointestinal stromal tumor: what is the same and what is different from global guidelines

There are some disparities between the clinical practice and profiles of cancer in Asia and those in Europe & North America. In Asia, surgical oncologists still have a major role in the multidisciplinary therapy of gastrointestinal stromal tumor (GIST), whereas medical oncologists hold this status in the West. Although the incidence of clinical GIST is considered similar between the two areas, small gastric GISTs are more frequently treated by surgery in East Asia compared with Europe & North America. The diagnosis and treatment of small submucosal tumors (SMTs), including GIST, is important in Asian clinical practice guidelines for GIST. Most items of Asian and Western GIST guidelines are very similar. There are slight differences between the two guidelines in the degree of recommendation, which may come from disparities of clinical practice and available medicines. Importantly, most clinical evidence in the GIST guidelines has been established by clinical trials conducted in Western countries, and the number of clinical trials is still limited in Asia, suggesting that Asian GIST patients may have limited access to investigational drugs after standard therapy. Finally, both Asian and Western GIST guidelines are well-harmonized in some parts, and their contents may reflect the medical circumstances of each region.

Impact of a risk-based follow-up in patients affected by gastrointestinal stromal tumour

BACKGROUND

Follow-up aims to precociously identify recurrences, metastases or treatment-related adverse events so as to undertake the appropriate therapy. Guidelines admit lack of knowledge on optimal surveillance schedule, but suggest follow-up based on experts' opinion and risk stratification. To identify the impact, if any, of regular follow-up, we interrogated our prospectively collected database whether early detection of recurrences affected both clinical management and, likely, the outcome.

PATIENTS AND METHODS

We required information to be available on primary surgery and ≥3°years of follow-up for non-recurring patients. We analysed recurrence characteristics (asymptomatic versus symptomatic, low- versus high tumour burden) and computed tomography (CT) scan counts to detect one recurrence. Kaplan-Meier method estimated recurrence-free survival (RFS), post-recurrence progression-free survival (PR-PFS), and disease-specific overall survival (OS). Comparisons used Hazard ratios (HR) with 95% confidence intervals (CIs). Multivariate analyses employed the Cox proportional hazards model. All tests were two-sided.

RESULTS

Between 01/2001 and 12/2012 we found 233 study-eligible patients. Estimated 5- and 10-year RFS were 61.8% and 50.4%, respectively. After a 68-month median follow-up, we observed 94 (40.3%) recurrences [73/94 (77.7%) asymptomatic versus 21/94 (22.3%) symptomatic and 45/94 (47.9%) low- versus 49/94 (52.1%) high tumour burden]. Multivariate analysis revealed that symptomatic and high tumour burden recurrences were highly predictive of both worse PR-PFS (HR:3.19, P < 0.001; HR:2.80, P = 0.003, respectively) and OS (HR:3.65, P < 0.001; HR:2.38, P = 0.026, respectively). Finally, 29 second (primary) cancers were detected during follow-up.

CONCLUSIONS

Regular follow-up detects recurrences at an earlier stage and may be associated with a better PR-PFS and OS for these patients. In the absence of randomised trials, these evidences support follow-up effort and cost.

Evidence-Based Cancer Imaging

With the advances in the field of oncology, imaging is increasingly used in the follow-up of cancer patients, leading to concerns about over-utilization. Therefore, it has become imperative to make imaging more evidence-based, efficient, cost-effective and equitable. This review explores the strategies and tools to make diagnostic imaging more evidence-based, mainly in the context of follow-up of cancer patients.

Update on Gastrointestinal Stromal Tumors for Radiologists

The management of gastrointestinal stromal tumors (GISTs) has evolved significantly in the last two decades due to better understanding of their biologic behavior as well as development of molecular targeted therapies. GISTs with exon 11 mutation respond to imatinib whereas GISTs with exon 9 or succinate dehydrogenase subunit mutations do not. Risk stratification models have enabled stratifying GISTs according to risk of recurrence and choosing patients who may benefit from adjuvant therapy. Assessing response to targeted therapies in GIST using conventional response criteria has several potential pitfalls leading to search for alternate response criteria based on changes in tumor attenuation, volume, metabolic and functional parameters. Surveillance of patients with GIST in the adjuvant setting is important for timely detection of recurrences.

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.

Knowns and Known Unknowns of Gastrointestinal Stromal Tumor Adjuvant Therapy

The first 15 years of management of gastrointestinal stromal tumor (GIST) have led to 3 lines of therapy for metastatic disease: imatinib, sunitinib, and regorafenib. In the adjuvant setting, imatinib is usually given for 3 years postoperatively to patients with higher-risk primary tumors that are completely resected. In this review, issues regarding GIST adjuvant therapy are discussed. It is hoped this review will help the reader understand the present standard of care to improve upon it in years to come.

The standard diagnosis, treatment, and follow-up of gastrointestinal stromal tumors based on guidelines

Although gastrointestinal stromal tumors (GISTs) are a rare type of cancer, they are the commonest sarcoma in the gastrointestinal tract. Molecularly targeted therapy, such as imatinib therapy, has revolutionized the treatment of advanced GIST and facilitates scientific research on GIST. Nevertheless, surgery remains a mainstay of treatment to obtain a permanent cure for GIST even in the era of targeted therapy. Many GIST guidelines have been published to guide the diagnosis and treatment of the disease. We review current versions of GIST guidelines published by the National Comprehensive Cancer Network, by the European Society for Medical Oncology, and in Japan. All clinical practice guidelines for GIST include recommendations based on evidence as well as on expert consensus. Most of the content is very similar, as represented by the following examples: GIST is a heterogeneous disease that may have mutations in KIT, PDGFRA, HRAS, NRAS, BRAF, NF1, or the succinate dehydrogenase complex, and these subsets of tumors have several distinctive features. Although there are some minor differences among the guidelines--for example, in the dose of imatinib recommended for exon 9-mutated GIST or the efficacy of antigen retrieval via immunohistochemistry--their common objectives regarding diagnosis and treatment are not only to improve the diagnosis of GIST and the prognosis of patients but also to control medical costs. This review describes the current standard diagnosis, treatment, and follow-up of GISTs based on the recommendations of several guidelines and expert consensus.

Follow-up strategies for patients with gastrointestinal stromal tumour treated with or without adjuvant imatinib after surgery

BACKGROUND

Patients with gastrointestinal stromal tumour (GIST) are often followed up after surgery with longitudinally repeated imaging examinations to detect recurrence early. Studies on follow-up of GIST patients are few, the optimal follow-up methods are unknown and the recommendations for follow-up vary in guidelines.

METHODS

We reviewed the current evidence for follow-up of patients treated with surgery alone and of patients who were treated with adjuvant or neoadjuvant imatinib.

RESULTS

Imaging of the abdomen and the pelvis with computerised tomography (CT) or magnetic resonance imaging (MRI) usually suffices, since metastases are uncommon at other sites. The frequency of imaging may be adjusted with the risk of recurrence with time. Very low risk GISTs are very frequently cured with surgery and usually require no regular follow-up after complete surgery, and annual CT of the abdomen and the pelvis for 5 years suffices for most patients with a low to intermediate risk for recurrence. Most high-risk patients are treated with imatinib for at least 3 years after surgery. CT or MRI may be carried out 6-monthly during adjuvant imatinib, 3 to 4-monthly during the 2 years that follow discontinuation of imatinib when the risk of recurrence is high, and then at 6-12 month intervals to complete 10 years of follow-up. Recurrence after the first 10 years of follow-up is infrequent.

CONCLUSIONS

The follow-up schedules are best tailored with the risk of recurrence. The risk of recurrence should be estimated with the prognostic tools that consider the most relevant prognostic factors.