Uptake of radiolabeled somatostatin analog is detectable in patients with metastatic foci of sarcoma
Abstract
BACKGROUND: Somatostatin receptors are present on many types of epithelial tumors, and ligands targeting these receptors are used to treat patients with neuroendocrine malignancies. Preclinical studies have demonstrated the presence of somatostatin receptors on a variety of mesenchymal tumors by in vitro receptor autoradiography. The use of radiolabeled somatostatin analogs to assess the presence of somatostatin receptors in vivo has been established, but use of this technique to evaluate human sarcomas has not been reported previously.
METHODS: Seventeen patients (13 females and 4 males) with metastatic sarcoma underwent imaging via somatostatin-receptor scintigraphy. Scans were performed using indium -111 pentetreotide. Planar studies and single photon emission computed tomography imaging were performed at 4 and 24 hours, and results of scintigraphy were correlated with computed tomography findings.
RESULTS: Twelve of 17 scans showed increased uptake in regions of known metastatic disease. There was no apparent correlation with scan positivity and patient age, histology, site of disease, or duration of diagnosis.
CONCLUSIONS: Seventy-one percent of patients with advanced soft-tissue sarcomas had positive scintigraphy scans demonstrating tumor expression of somatostatin receptors subtype 2 in vivo. Imaging with indium-111 pentetreotide could be studied as an adjunct to conventional imaging modalities for assessment of sarcoma patients. Further research is needed to determine the prognostic implications of somatostatin receptor subtype 2 positivity, including larger studies to evaluate any potential correlation with metastatic behavior and other clinical outcomes.
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