The role of octreotide imaging in detecting neuroendocrine tumors (NETs) in 2010: Do we still need it?

Abstract

4032 Background: Somatostatin scintigraphy (OctreoScan, SRS) detects somatostatin receptors and images disease in patients with NETs. We sought to evaluate the utility of SRS when used in conjunction with modern CT or MRI and to determine if it added information to the CT or MRI. Methods: Electronic medical records identified all patients who underwent either a CT or MRI in addition to SRS within a 30-day time period at MSKCC (1/1/2003-6/11/2008). Reports of the SRS and CT/MRI were reviewed. Results: 104 patients were identified. 13 cases were nonevaluable and were excluded (1 merkel cell,1 unknown primary, 4 CT scans performed postsurgery with SRS performed pre-op, 3 patients with NET plus a second primary malignancy, 4 patients that had a limited CT for biopsy purposes). Of the 91 evaluable patients, 16 had functional tumors and 81 had metastatic disease. Nineteen were high grade, 7 intermediate grade, 56 low grade and 9 had no grade classification. There were 6 patients that had serial SRS plus either CT or MRI within a 30 day window. 18 patients had a negative SRS in the setting of clear metastatic disease on CT or MRI. Of those, 12 were high grade, 1 intermediate grade, 3 low grade and 2 unspecified. Notably, SRS missed hepatic metastases in 14 patients, in which, for 6 patients, this was their sole site of metastases. An additional 18 patients had findings on CT or MRI not seen on SRS and the liver was one of the most common sites missed. Four patients had positive findings on SRS that were not seen on CT or MRI imaging; all of these findings were bone lesions. None of the bone lesions were clinically relevant, defined as lesions that changed the clinical regimen, and all were in the setting of metastatic disease. Of the 6 patients who underwent serial SRS and CT or MRI, SRS did not detect any additional metastatic disease. Conclusions: Modern CT and MRI were able to identify soft tissue lesions with greater sensitivity than SRS. 5% of patients had clinically insignificant SRS avid bone metastases not seen on CT or MR. These data suggest that SRS is not a useful adjunct to defining extent of disease in NET tumors, and should not be used routinely for this purpose. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Alchemia, Biothera, Delcath, ImClone Systems, Merck, Novartis, Roche Pfizer Amgen, Biothera, Bristol-Myers Squibb, Curetech, Genentech, ImClone Systems, Lilly, Merck, Pfizer, Roche, Tercica