[Importance of PET for surgery of gastrointestinal stromal tumors]

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the digestive tract. The GIST differ substantially from gastrointestinal carcinomas regarding tumor biology, treatment strategies and indications for surgery. Every surgeon involved in the treatment of GIST should be acquainted with these aspects.

The aims of this article are to discuss the value of positron emission tomography (PET) in the surgical treatment of patients with GIST and to provide an outlook on the development of molecular tracers specifically tailored for GIST.

PET is an invaluable decision aid in the multimodal therapy of GIST and particularly for deciding on surgical indications. Specific scenarios in which PET is used are primary staging monitoring during neoadjuvant therapy and staging and response assessment in the metastatic setting. The routinely used tracer is 18F-fluorodeoxyglucose (18F-FDG) and uptake reliably correlates with the metabolism of GIST lesions. Compared to computed tomography and magnetic resonance imaging (CT/MRI), 18F-FDG-PET often allows a more timely and accurate response assessment. GIST-specific molecular tracers, which could provide a direct prognosis regarding response and development of resistance to treatment, are currently in preclinical development. However, pharmacokinetic and immunological issues still need to be resolved. A distant aim is the development of "theranostics", i.e. substances which serve both diagnostic and therapeutic purposes.

PET has an established value in the multimodal treatment of GIST and is particularly useful for deciding on surgical indications.