Radionuclide-labeled somatostatin analogues for diagnostic and therapeuticpurposes in nonmedullary thyroid cancer

Despite the fact that several recent studies report an expression of somato statin receptors in nonmedullary thyroid cancer (non-MTC), there is still n o consensus concerning the diagnostic and therapeutic usefulness of radionu clide-labeled somatostatin analogues in non-MTC. We present the results of 50 scintigraphic studies with In-111-Pentetreotide (In-111-P) in 48 patient s with metastasizing non-MTC (n = 9 papillary, n = 9 follicular, n = 29 Hur thle cell, n = 1 insular carcinoma). The findings were compared with histol ogy and with other imaging modalities. In-111-P provided unequivocally posi tive 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 thyro globulin > 10 ng/mL). Histopathology demonstrated that maximal uptake was o bserved in Hurthle cell carcinoma (95% positive examinations if thyroglobul in exceeds 10 ng/mL). We also describe for the first time dosimetric and cl inical data from the courses of Y-90-DOTATOC therapy in three patients with progressive, somatostatin-receptor-positive non-MTC (up to 9.3 GBq per 4 c ycles). Tumor progression could not be stopped in any of the patients treat ed with Y-90-DOTATOC. We conclude that In-111-P is a promising tool for who le-body diagnosis in nonradioiodine-accumulating non-MTC, especially in Hur thle cell cancer, and if 2-[F-18]fluorodeoxyglucose-positron emission tomog raphy (FDG-PET) is not available. Although the number of patients treated w ith Y-90-DOTATOC is still limited, our applied treatment protocol appears t o be ineffective in metastasizing non-MTC.