Radionuclide-Labeled Somatostatin Analogues for Diagnostic and Therapeutic Purposes in Nonmedullary Thyroid Cancer

Abstract

Despite the fact that several recent studies report an expression of somatostatin receptors in nonmedullary thyroid cancer (non-MTC), there is still no consensus concerning the diagnostic and therapeutic usefulness of radionuclide-labeled somatostatin analogues in non-MTC. We present the results of 50 scintigraphic studies with ¹¹¹In-Pentetreotide (¹¹¹In-P) in 48 patients with metastasizing non-MTC (n = 9 papillary, n = 9 follicular, n = 29 Hürthle cell, n = 1 insular carcinoma). The findings were compared with histology and with other imaging modalities. ¹¹¹In-P provided unequivocally positive results in 37 of 50 (74%) of the patients (27% in the 11 patients with current thyroglobulin levels <10 ng/mL and 85% in the patients with thyroglobulin >10 ng/mL). Histopathology demonstrated that maximal uptake was observed in Hürthle cell carcinoma (95% positive examinations if thyroglobulin exceeds 10 ng/mL). We also describe for the first time dosimetric and clinical data from the courses of ⁹⁰Y-DOTATOC therapy in three patients with progressive, somatostatin-receptor-positive non-MTC (up to 9.3 GBq per 4 cycles). Tumor progression could not be stopped in any of the patients treated with ⁹⁰Y-DOTATOC. We conclude that ¹¹¹In-P is a promising tool for whole-body diagnosis in nonradioiodineaccumulating non-MTC, especially in Hürthle cell cancer, and if 2-[¹⁸F]fluorodeoxyglucose-positron emission tomography (FDG-PET) is not available. Although the number of patients treated with ⁹⁰Y-DOTATOC is still limited, our applied treatment protocol appears to be ineffective in metastasizing non-MTC.