A Review of Prostate-Specific Membrane Antigen (PSMA) Positron Emission Tomography (PET) in Renal Cell Carcinoma (RCC).

Metastatic renal cell carcinoma (mRCC) is a disease that portends poor prognosis despite an increasing number of novel systemic treatment options including new targeted therapies and immunotherapy. Ablative intervention directed at oligometastatic RCC has demonstrated survival benefit. Consequently, developing techniques for improved staging of mRCC on contemporary imaging modalities including X-ray computed tomography (CT), magnetic resonance imaging (MRI) and/or bone scan (BS) is a clinical priority. This is relevant for metastatic deposits too small to characterize or lymph nodes within physiological normality. Prostate-specific membrane antigen (PSMA) is a type II transmembrane glycoprotein highly expressed on prostate cancer epithelial cells. Recently, small molecules targeting the PSMA receptor, linked to radioactive isotopes have been developed for use with positron emission tomography (PET). Despite its nomenclature, PSMA has also been found to be expressed in the neovasculature of non-prostate cancers such as renal cell carcinoma (RCC) and hence PSMA PET/CT imaging has been proposed as an alternative staging modality. Preliminary small studies involving the use of PSMA PET/CT imaging in mRCC have been encouraging with evidence of improved staging sensitivity which has directly led to change in management in some cases. Given these early encouraging reports, we performed a comprehensive narrative review on the available evidence, including the scientific basis for PSMA expression in RCC, the role of PSMA PET/CT imaging with potential clinical implications in mRCC, its limitations and future opportunities.