68Ga-DOTATOC PET/CT and 90Y-DOTATOC therapy: Perspectives for patients with metastatic radioiodine negative differentiated thyroid cancer

Abstract

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Objectives: Many patients (pts) with distance metastases (mts) from differentiated thyroid carcinoma (DTC) lose in time the capacity to concentrate radioiodine and the management is difficult. DTC may express somatostatin receptors (SSTRs); this offers the base for new strategies of diagnosis and treatment. Aim of the study is to evaluate the utility of somatostatin analog DOTA-D-Phe1 -Tyr3-octreotide (DOTATOC), radiolabelled with 68Ga for PET/CT and with 90Y for therapy, in these pts.

Methods: We studied 7 pts (m/f 3/4; age 47-73 yrs, mean 65.7) with non-radioiodine-avid DTC, metastatic or suspicious metastatic. All pts underwent 68Ga-DOTATOC PET/CT: two of these (Hurthle cell and insular carcinoma respectively) with high uptake mts had 90Y- DOTATOC treatment.

Results: Four pts were PET-positive (2 pts with Tg >6000 ng/ml: high uptake respectively in multiple lung and bone mts; 1 pt: moderate uptake in sternal lesion; 1 pt: low uptake in neck recurrence) and 3 pts with lung mts were PET-negative. The 2 pts with high PET positivity underwent 90Y- DOTATOC therapy. Two months after the first administration (1670 and 1300 MBq respectively) the pt with lung mts has a good improvement of dispnea while the pts with bone mts is stable; they had no significant side effect.

Conclusions: 68Ga-DOTATOC PET/CT is an interesting diagnostic tool for the evaluation of pts with progressive radioiodine-negative DTC. The possibility to use the same peptide for therapy in PET positive pts is promising but needs further confirmation.