Prostate-Specific Membrane Antigen Expression in Patients With Differentiated Thyroid Cancer With Thyroglobulin Elevation and Negative Iodine Scintigraphy Using 68Ga-PSMA-HBED-CC PET/CT

Abstract

Purpose of the Report Prostate-specific membrane antigen (PSMA) is a member of superfamily of zinc-dependent exopeptidases that is robustly expressed in prostate cancer cells and nonprostatic solid tumor neovasculature including microvessels of thyroid tumors. Its expression in differentiated thyroid cancer (DTC) has been confirmed in many recent studies, but systematic studies exploring PSMA expression in patients with DTC with thyroglobulin elevation and negative iodine scintigraphy (TENIS) are lacking. The aim of the present study was to evaluate the role of PSMA scan in TENIS patients with DTC. Methods Nine consecutive patients with DTC with proven TENIS syndrome (6 men and 3 women with age range 29–68 years and mean age of 48 years) underwent 18F-FDG PET/CT as per the institution protocol. Thereafter, they were subjected to 68Ga-PSMA-HBED-CC PET/CT as per the institution protocol within a week of FDG PET imaging. Prostate-specific membrane antigen expression (SUVmax) in the lesions was compared with 18F-FDG PET and CT scan findings. Results In 5 of 9 patients with TENIS, the metastatic lesions showed PSMA expression. A total of 14 lesions were seen on the CT scan. Prostate-specific membrane antigen PET detected 9 of 14 lesions (64.28%) (SUVmax ranging from 10.1 to 45.67; median SUVmax of 16.31), whereas FDG PET was positive in 11 of 14 lesions (78.57%). The lesions that showed PSMA uptake was localized to bones (5 of 9) and lungs (4 of 9). Two lesions that were localized to iliac crest and acetabulum were missed on FDG PET but were seen on CT and PSMA PET scan. Conclusions The results of this pilot study indicate that 68Ga-HBED-CC-PSMA PET/CT demonstrates PSMA expression in TENIS patients with lesions being localized to the bones and lungs. 68Ga-PSMA PET/CT could be useful for the identification of TENIS patients who might benefit from PSMA-targeted radionuclide therapy.

PSMA Radioligand Uptake as a Biomarker of Neoangiogenesis in Solid Tumours: Diagnostic or Theragnostic Factor?

“…Six full-text papers assessing the potential role of PSMA radioligands in the diagnostics and therapy of differentiated thyroid cancer (DTC) were reviewed [ 40 , 41 , 42 , 43 , 44 , 45 ]. Out of the six included studies, four had a prospective design [ 40 , 42 , 43 , 45 ]. The sample size varied from 2 to 11 and from 3 to 43 for patient and lesion analyses, respectively.…”

“…In all studies but one [ 40 , 41 , 42 , 43 , 44 ], PET/CT was performed using 68 Ga-PSMA-11, whereas the remaining study used 18 F-DCFPyl [ 45 ]. In one study, in addition to 68 Ga-PSMA-11 PET/CT as diagnostic compound, 177 Lu-PSMA-617 RLT therapy was performed in two out of five patients [ 41 ].…”

“…The main DTC investigated histotype was papillary thyroid cancer, as overall a total of 27 patients were examined; further DTC subtypes included were follicular (10 patients), Hürtle cell (2 patients) and anaplastic carcinomas (2 patients). All of the available literature concerning the employment of PSMA radioligands in thyroid cancer focuses on radioiodine-refractory DTC patients [ 40 , 41 , 42 , 43 , 44 , 45 ].…”

Theranostic Options for Radioiodine-Refractory Differentiated Thyroid Carcinoma: Recent Advances, Challenges, and Road Ahead

“…However, in another series comprising nine patients with TENIS syndrome, the authors reported PSMA-positive disease in only 5/9 (56%) patients compared to FDG-positive disease in 8/9 (89%) patients. Further, out of a total of 14 lesions, [ 68 Ga]Ga-PSMA-11-PET/CT detected less lesions compared to 2-[ 18 F]FDG-PET/CT (9/14 versus 11/14, respectively) ( 23 ). Given the lower detection rates, the role of [ 68 Ga]Ga-PSMA-11-PET/CT in RAIR-DTC lies primarily in patient selection for [ 177 Lu]Lu-PSMA-617 therapy, and not for diagnostic purposes.…”

Positron Emission Tomography Radiopharmaceuticals in Differentiated Thyroid Cancer

“…Metastatic lesions in RAI-refractory DTC patients were demonstrated by PET/CT using 68 Ga-based PSMA, which found additional metastatic lesions compared with [ 18 F]FDG [ 60 , 61 , 62 ]. Vries et al treated two RAI-refractory DTC patients with [ 177 Lu]Lu-PSMA-617.…”