Current treatment and outcomes of pediatric gastrointestinal stromal tumors (GIST): a systematic review of published studies

Surgical management of rare tumors (Part 1)

With an annual cumulative occurrence of approximately 15,000 in North America, all childhood cancers are rare. Very rare cancers as defined by both the European Cooperative Study Group for Rare Pediatric Cancers and the Children's Oncology Group fall into two principal categories: those so uncommon (fewer than 2 cases/million) that their study is challenging even through cooperative group efforts (e.g., pleuropulmonary blastoma and desmoplastic small round cell tumor) and those that are far more common in adults and therefore rarely studied in children (e.g., thyroid, melanoma, and gastrointestinal stromal tumor). Treatment strategies for these latter tumors are typically based on adult guidelines, although the pediatric variants of these tumors may harbor different genetic signatures and demonstrate different behavior. If melanoma and differentiated thyroid cancer are excluded, other rare cancer types account for only 2% of the cancers in children aged 0 to 14. This article highlights several of the most common rare tumor types.

From KIT-mutated into wild-type: dedifferentiation of gastrointestinal stromal tumor in adolescent patient-a case report

Background

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the gastrointestinal tract, usually found in elderly adults. It is infrequent among pediatric patients and usually differs from adult-type disease in terms of histopathology and molecular features.

Case Description

We describe the management of the disease in a 10-year-old female patient diagnosed with a GIST of the stomach. In total, she has undergone successively total tumor resection, unsuccessful imatinib treatment and subtotal gastric resection at relapse. The first genetic test from primary tumor confirmed KIT mutations in exons 13 and 17, while the repeated genetic screening using tumor sample from subtotal gastric resection revealed no KIT or platelet-derived growth factor receptor α (PDGFRA) genes mutations. Such dedifferentiation from adult type (thus KIT-mutated) into wild-type (without KIT or PDGFRA mutation) has not been reported so far to the best of our knowledge. Currently, the patient is observed, and no further pharmacological nor surgical treatment has been administered.

Conclusions

The case underlines the importance of genetic profiling combined with non-standard diagnostics (both histopathological and radiological) due to the treatment efficacy prediction. We moreover emphasize the necessity to create worldwide standards on the diagnostics and treatment of GIST in pediatric patients that would include options of targeted therapies.

Latest Advances in the Management of Pediatric Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumor is the most common mesenchymal neoplasm of the gastrointestinal tract, usually found in elderly adults. It is infrequent among pediatric patients and usually differs biologically from adult-type diseases presenting mutations of KIT and PDGFR genes. In this population, more frequent is the wild-type GIST possessing SDH, TRK, RAS, NF1 mutations, among others. Both tumor types require individualized treatment with kinase inhibitors that are still being tested in the pediatric population due to the different neoplasm biology. We review the latest updates to the management of pediatric gastrointestinal tumors with a particular focus on the advances in molecular biology of the disease that enables the definition of possible resistance. Emerging treatment with kinase inhibitors that could serve as targeted therapy is discussed, especially with multikinase inhibitors of higher generation, the effectiveness of which has already been confirmed in the adult population.