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

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.