Somatostatin Receptor Scintigraphy in Patients with Carcinoid Tumors

Abstract. In 80% to 90% of patients with carcinoids, tumor sites can be detected with [¹¹¹In-DTPA-d-Phe¹]-octreotide scintigraphy. Unexpected, additional localizations are reported in one-third to two-thirds of patients. In a group of 52 patients, we analyzed the results of various combinations of octreotide scintigraphy and conventional imaging. Octreotide scintigraphy, alone or in combination with other imaging modalities, led to the detection of more tumor sites than any combination of conventional imaging techniques. The combination of octreotide scintigraphy, chest radiography, and ultrasonography of the upper abdomen led to the detection of lesions in all patients in whom they could be demonstrated by any imaging means, with a sensitivity of 87% in terms of the number of detected lesions. The calculated cost for this imaging regimen was higher than for the combination of conventional imaging as applied in our group. However, the benefit was the detection of at least one lesion in 11% of patients in whom with conventional imaging no abnormalities were found. Moreover, if the results from our patient group were extrapolated to a group of 100 patients, the advantage in terms of the number of extra lesions detected would be 65 extra lesions per 100 patients. The detection of more tumor sites in patients who are known to have one tumor localization with conventional imaging may be essential when deciding whether to perform surgery. Octreotide scintigraphy can be used to localize tumors, direct the choice of medical therapy, and (expected in the near future) select patients for radiotherapy. The impact on patient management is fourfold: Octreotide scintigraphy may detect resectable tumors that would be unrecognized with conventional imaging techniques; it may prevent surgery in patients whose tumors have metastasized to a greater extent than can be detected with conventional imaging; it may direct the choice of therapy in patients with inoperable tumors; and in the future it may be used to select patients for radionuclide therapy.