The Use of Ga-PET/CT PSMA in the Staging of Primary and Suspected Recurrent Renal Cell Carcinoma

Purpose: The role of Ga-PSMA PET/CT in the staging of prostate cancer is well known. PSMA is also overexpressed in the neovasculature of other tumours including renal cell carcinoma (RCC), suggesting there may be a role for the use of Ga-PSMA PET/CT. Thus far, there has been limited literature documenting the use of Ga-PSMA PET/CT in the investigation and management decisions of RCC.

Methods: This was a retrospective case series of patients who received a Ga-PSMA PET/CT scan for staging or restaging of RCC between July 2016 and December 2018. Primary outcome measure was to identify whether Ga-PSMA PET/CT changed management compared to standard diagnostic CT imaging. Analysis was based on four categories: (1) identification of new disease, (2) refuting disease on CT imaging, (3) identification of synchronous primaries, and (4) concordance with CT imaging.

Results: 38 Ga-PSMA PET/CT scans met inclusion criteria. Primary staging scans were performed in 16 patients, of which 75% showed avid primary lesions, with the majority of clear cell subtype. Management was changed in 43.8% of patients. CT agreed with Ga-PSMA PET/CT in 37.5% of cases. Restaging scans were performed in 22 patients. 40.9% of patients had management changed by results of Ga- PSMA PET/CT. CT agreed with Ga- PSMA PET/CT in 36.4% of cases. Management was predominantly changed due to the identification of new sites of suspected metastases, as well as the detection of synchronous primaries.

Conclusions: Ga-PSMA PET/CT directly changed management in 42.1% of cases. Strongest detection rates occurred in those patients with clear cell RCC. The results of this study suggest there may be merit in the use of the modality in the staging of RCC. Further analysis, both with respect to histological confirmation, efficacy and cost-benefit, is required to determine whether there is a role for routine Ga-PSMA PET/CT imaging.