PET scan for GIST – pro

PET is often used for staging and monitoring of response for GIST tumors. A recent consensus statement says: “The panelists agreed that currently available imaging techniques to evaluate GIST include computed tomography (CT), magnetic resonance imaging (MRI) and fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography (PET). ”

The journal Applied Radiology (vol. 34, no. 6, 2005), in an article titled ‘Role of Positron Emission Tomographic Imaging in Gastrointestinal Stromal Tumors,’ cited case studies where PET ‘helped in accurate re-staging by indicating the malignant nature of the hepatic and subhepatic masses and excluding pelvic spread.’ The article also noted that, ‘when compared with CT alone, PET with FDG and PET/CT provided valuable additional information about the extent and metabolic activity of the disease process. … The advantage of PET lies in its ability to differentiate active tumor from a nonviable necrotic tumor mass, malignant from benign tissue, and recurrent tumor from scar tissue.’   Unfortunately, however, there is little support for PET in GIST beyond case reports and studies.

The aforementioned consensus statement concluded: ” Evaluation of FDG uptake using PET scanning is recommended when an early detection of tumor response to imatinib treatment is required, e.g. for consideration of surgery after imatinib cytoreduction in rectal tumors (SOR expert opinion, NCCN level 2A). PET scan may also be useful in case of equivocal images suspected to be metastatic. Aside from these cases, PET scan is not mandatory in all GIST patients after complete resection (SOR expert agreement, NCCN level 2A). ”

A 2010 review (Reishardt et al) says: :

“Contrast-enhanced abdominal and pelvic CT scan is the technique of choice for staging and follow-up. A chest x-ray can complement staging and work-up. MRI should be used in rectal GIST as it provides better preoperative staging information. PET or PET–CT/MRI is not routinely required but may be useful for early detection of tumor response during neoadjuvant treatment.uld approve CT or PET for staging”.

Peter Reichardt, Jean-Yves Blay, Margaret von Mehren,Towards Global Consensus in the Treatment of Gastrointestinal Stromal TumorExpert Rev Anticancer Ther. 2010;10(2):221-32.

Van den Abbeele AD, Badawi RD, Cliche JP et al. 18F-FDG-PET predicts response to imatinib mesylate (Gleevec) in patients with advanced gastrointestinal stromal tumors (GIST). Proc Am Soc Clin Oncol 2002; 21: 403a (Abstr 1610).

Stroobants S, Goeminne J, Seegers M et al. 18FDG-Positron emission tomography for the early prediction of response in advanced soft tissue sarcoma treated with imatinib mesylate (Imatinib). Eur J Cancer 2003; 39: 2012–2020.

Antoch G, Kanja J, Bauer S et al. Comparison of PET, CT, and dual-modality PET/CT imaging for monitoring of imatinib (STI571) therapy in patients with gastrointestinal stromal tumors. J Nucl Med 2004; 45: 357–365.

Choi H, Macapinlac H, Burgess M et al. Correlation of computerized tomography (CT) and proton emission tomography (PET) in patients with metastatic GIST treated at a single institution with imatinib mesylate. Proc Am Soc Clin Oncol 2003; 22: 819.

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