[Gastrointestinal stromal tumour (GIST): current standards in multimodal management]

Abstract

Gastrointestinal stromal tumours (GIST) are the most frequent mesenchymal tumours of the gastrointestinal tract. The gold standard therapy is their complete surgical removal with safety margins of 1-2 cm. Intraoperative damage to the tumour must be avoided because tumour rupture carries a very high risk of peritoneal spread. Since metastases to lymph nodes in general does not occur in GIST a lymph node dissection is not indicated. Depending on the size of the tumour, the number of mitoses and the localisation of the primary tumour, the risk of recurrence after potentially curative resection is considerable in many cases. Patients with intermediate and high risk according to Miettinens classification should receive adjuvant treatment with imatinib. Exceptions are those patients whose tumours exhibit a mutation in exon 18, D842V of PDGFRA. According to current data the therapy is continued for 3 years. This leads not only to a significant improvement of the progression-free survival in comparison to therapy for 1 year but also, especially, to an improvement of overall survivial. In the case of local advanced tumours that can only be resected by a mutilation operation, a primary systemic therapy with imatinib should be initiated on account of its extremely high efficacy. Standard therapy for local advanced or metastasizing GIST is imatinib at a dose of 400 mg/day. Patients with mutations in KIT exon 9 should be treated with 800 mg imatinib/day, since they profit from a significantly longer progression-free survival. Therapy with imatinib should always be continued up to progression or intolerance. In the case of progression under 400 mg imatinib the ESMO guidelines recommend a dose increase to 800 mg/day as about a third of the patients respond to this higher dose. In the case of further progression a switch to second-line therapy with sunitinib is recommended. After exploitation of all registered therapy options the patients should be offered an experimental therapy within the framework of a clinical trial.