Indium-111 octreotide scintigraphy for the detection of non-functioning metastases from differentiated thyroid cancer: diagnostic and prognostic value.

In this prospective study, we evaluated the diagnostic and prognostic value of (111)In-octreotide scintigraphy (SRS) in papillary and follicular thyroid carcinoma (DTC) with increasing thyroglobulin (Tg) levels but no response to treatment with (131)I. Twenty-three consecutive patients (13 female, 10 male; mean age 55 years, range 13-81 years) with progressive DTC were selected for the study. All patients had non-functioning metastases, defined by no or slight uptake of (131)I in metastases. Diagnosis of tumour progression was based on rising Tg levels during follow-up and was confirmed by radiological examination. Uptake on SRS was scored from 0 to 4. Data on initial tumour stage, histology, age, gender, Tg values, TSH levels, (131)I treatment doses, intervals and survival were gathered. Seven patients died during follow-up. The overall sensitivity for the detection of metastases was 74%. The sensitivity was better in patients in whom (131)I whole-body scintigraphy did not show any abnormal uptake (82%; 14/17) than in patients with faint (131)I uptake (50%; 3/6). The 10-year survival rate was significantly different between patients with an uptake score of 0 or 1 (100%) and those with an uptake score of 2, 3 or 4 (33%) ( P=0.001). Gender, log Tg and uptake on SRS significantly correlated with survival, but in stepwise analysis, (111)In-octreotide uptake was selected as the most prognostic independent variable (hazard rate 6.25, P=0.006). We conclude that (111)In-octreotide scintigraphy is a valuable clinical tool for the detection of non-functioning DTC metastases. The uptake seems to correlate with prognosis and survival.