Perspective on updated treatment guidelines for patients with gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract and present predominantly in middle-aged and older individuals. Historically, the outlook for patients with GISTs was very poor because of the general lack of efficacy of conventional chemotherapy and the often limited surgical options. However, the recognition of the role of mutations of the v-kit Hardy/Zuckerman 4 feline sarcoma viral oncogene homolog KIT and the platelet derived growth factor receptor alpha gene PDGFRα in the development of GISTs led to the evaluation of potential antitumor effects of the tyrosine kinase inhibitors imatinib and, more recently, sunitinib. Consequently, these molecularly targeted therapies were introduced into clinical practice, and the outcome for patients with GISTs improved considerably. In the last few years, the European Society of Medical Oncology, the National Comprehensive Cancer Network, and the Canadian Advisory Committee on GIST each published a major set of guidelines or practice recommendations for the management of patients with GIST. In the current review, the latest recommendations from each organization are summarized in terms of diagnosis and risk assessment, tumor staging, surgical and/or drug treatment of primary resectable and recurrent metastatic disease, and patient follow-up and assessment. In addition, areas of consensus and points of divergence among the guidelines are highlighted along with any unresolved issues.

The role of high-dose imatinib in the management of patients with gastrointestinal stromal tumor

After an era of few treatment options for patients with locally advanced or metastatic gastrointestinal stromal tumor (GIST), imatinib has emerged as the standard of care and first-line treatment for these patients. Although imatinib was initially approved at the doses of 400 and 600 mg daily, results from clinical studies established 400 mg daily as the standard initial dose for the majority of advanced GIST patients. Nevertheless, the use of high-dose imatinib (800 mg daily) has been shown to benefit patients with advanced or metastatic GIST that progresses on the standard-dose, and has been recommended in this setting by the major management guidelines in Europe and the United States. Results from the Meta-GIST meta-analysis showed that patients whose GIST harbors a KIT exon 9 mutation garner a longer progression-free survival time when treated initially with high-dose imatinib (800 mg daily) compared with those patients with KIT exon 11 or no mutations. Thus, the use of high-dose imatinib is recommended by the clinical practice guidelines in these 2 specific clinical situations. In addition, clinicians should weigh the clinical benefit of administering high-dose imatinib against the associated toxicities, as well as the proper management of dose-related side effects.

Role of surgery combined with kinase inhibition in the management of gastrointestinal stromal tumor (GIST)

BACKGROUND

Surgery is the standard treatment for primary, gastrointestinal stromal tumor (GIST); however, surgical resection often is not curative, particularly in large GIST. Five years after complete removal of their tumor, approximately half of treated patients relapse. Imatinib, an oral tyrosine kinase inhibitor (TKI), is first-line treatment in patients with metastatic or unresectable GIST. It has resulted in durable objective responses or stable disease in 84% of patients and is well tolerated. The efficacy of imatinib in advanced GIST has created interest in a variety of potential multimodal approaches to management that combine surgery with systemic therapy.

RESULTS

Recently, a large, randomized, Phase III, US cooperative group trial that compared adjuvant imatinib, for 1 year after primary complete surgical resection, with placebo in primary GIST, reported a significantly shorter time to relapse for those in the placebo group. This led to the approval of imatinib for this new indication in the US and Europe. Several studies evaluating the efficacy of adjuvant imatinib in patients with primary GIST who are at high risk for postoperative relapse are ongoing; in particular two large European studies are expected to yield preliminary results in the near future. Neoadjuvant therapy with imatinib is also being investigated for its effect on surgical outcomes, with first trial results reported.

CONCLUSION

This article provides an update on the rapidly evolving role of surgery, treatment with TKI therapy, and their combination in the management of GIST as well as further reviews pertinent to current clinical research findings.