PET/CT with 18F-PSMA-1007 in Diagnostics of Primary and Recurrent Lesions of Clear-cell Renal Cell Carcinoma in Comparison with 18F-FDG: Prospective Study

Introduction: Attempts have been made to use various RPs, other than 18 F-FDG in the diagnostics of renal cell carcinoma (RCC), with promising results demonstrated by PSMA-specific RPs, in particular 18 F-PSMA-1007. A prospective study was conducted at N.N. Blokhin NMRCO to establish capabilities of PET/CT with 18 F-FDG and 18 F-PSMA-1007 in primary and recurrent ccRCC diagnostics. Material and methods: Forty-eight patients were included in the study, 28 with renal masses and 20 with suspected local recurrence of ccRCC. Biopsy results were available in all patients. All patients underwent PET/CT with 18 F-PSMA-1007 and 18 F-FDG. Results: Thirty-nine renal neoplasms were identified in 28 patients. 24 of 39 foci (21 patients) were PSMA-positive and 18 of 39 foci (16 patients) were FDG-positive. No false-positive foci were identified. The sensitivity, specificity, positive and negative predictive value in primary RCC were: for 18 F-PSMA-1007 — 75, 100, 100 and 85 %, respectively; for 18 FDG — 57, 100, 100 and 76 %, respectively. The SUV max level of 18 F-PSMA-1007 exceeded 18 FDG in 27 of 28 patients (38 foci); the tumor/background ratio was higher in 16 of 28 patients (24 foci). Tumor thrombosis was detected in 6 patients (PSMA-positive 6 of 6, FDG-positive 5 of 6). PSMA-SUV max levels in thrombi exceeded 18 FDG in all patients, tumor/background ratio in 5 out of 6 patients. Local recurrence was detected in 13 of 20 patients (27 foci). 10 foci in the remaining 7 patients were considered as false positives. No false-negative results were obtained. Sensitivity, specificity, positive and negative predictive value in the diagnosis of local recurrence of ccPCC: 18 F-PSMA-1007 — 100, 94, 81 and 100 %, respectively; 18 FDG -100, 89, 68 and 100 %, respectively. SUV max and tumor/background ratio were found to correlate with primary tumor and recurrent node sizes for both RPs. Discussion and conclusions: At the moment, the role of 18 F-PSMA-1007 in RCC diagnostics has not been defined. We can note the high efficiency of this RP in the assessment of the primary focus and recurrence of ccRCC, its usage is justified in cases, when routine diagnostic methods do not give an unambiguous answer. The possibilities of 18 F-PSMA-1007 in metastatic ccRCC diagnostics are of the greatest interest. A significant prospective material has been collected in our department, which will be the basis for further study of this RP in the diagnostics of metastatic ccRCC.