Non-Invasive Molecular Imaging and its Impact on Management of the Localized Disease and Suspected Recurrence

Andrei H. Iagaru, MD, FACNM, Professor of Radiology and Chief of the Division of Nuclear Medicine and Molecular Imaging at Stanford University, enumerates the applications of a dual radiopharmaceutical-targeted imaging approach using prostate-specific membrane antigen (PSMA) and gastrin-releasing peptide receptor (GRPR) in prostate cancer care. He explains that while PSMA-targeted PET imaging is more widely accepted, GRPR-targeted imaging may identify tumors that PSMA-targeted PET misses and vice versa. Therefore, combining the two can give clinicians a clearer understanding of the patient’s cancer. Dr. Iagaru suggests that the dual target approach can be particularly helpful in guiding biopsy decisions in patients with suspected prostate cancer, as well as in helping identify all lesions prior to local therapy with high-intensity focused ultrasound (HIFU) or brachytherapy. Using two targets can also sometimes allow clinicians to find more lesions prior to prostatectomy and pelvic lymph node dissection. He notes that targeting GRPR with 68Ga-RM2 can be particularly useful in patients with biochemical recurrence, since PSA velocity is higher in 68Ga-RM2 positive scans than in 68Ga-RM2 negative scans. Dr. Iagaru concludes by considering the potential of these two targets in theranostics, noting that phase 3 trials of theranostics with PSMA are awaiting results and that phase 1 and 2 trials of theranostics with GRPR are promising.

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