Prostate-specific Membrane Antigen-PET/CT in Nonprostatic Malignancies: Potential Applications in Theranostics

68Gallium-prostate-specific membrane antigen (PSMA) PET/CT has evolved as a pivotal imaging modality for prostatic carcinoma. Prostate-specific membrane antigen (PSMA) is a zinc-dependent peptidase and a type II membrane protein that is expressed in prostate cancer and also tumor neovasculature of various nonprostatic malignancies. Recently, there have been many studies to demonstrate the expression of PSMA in vivo in nonprostatic malignancies like glioma, renal cell carcinoma, differentiated thyroid carcinoma, lung cancer, breast cancer, and salivary gland tumors, among others, and explore the diagnostic and therapeutic utility in these malignancies. While they have shown promising results with some even providing better imaging results than 18F-fluorodeoxyglucose PET/CT, it is important to evaluate the indications where PSMA PET/CT can be utilized efficiently. We must also be mindful of the benign conditions where PSMA uptake can be observed while we analyze the scans. In this review, we have described the clinical exploration of PSMA-based PET/CT in the imaging of various cancers and potential therapeutic applications.