Evolving Role of PSMA PET/CT in Clinically Localized Prostate Cancer

Conventional imaging for prostate cancer — computed tomography (CT) scans of the abdomen and pelvis and bone scans — has long been used to determine the presence or absence of metastatic disease in men with clinically localized disease with high-risk features. The recent FDA approvals of both gallium- and fluoride-based prostate-specific membrane antigen (PSMA) PET/CT in men with biochemical recurrence was based on trials demonstrating higher detection rates than obtained with conventional imaging.

In a prospective, single-arm, phase 3 study at two institutions, patients with intermediate- to high-risk disease being evaluated for radical prostatectomy each underwent a ⁶⁸Ga-PSMA-11 PET study using either PET/CT or PET/MRI. Images were interpreted by nuclear medicine physicians and the reports were sent to the referring physician, who could use the results to make treatment decisions.

Of 764 patients enrolled, 277 (36%) underwent prostatectomy and node dissection, of whom 75 (27%) had pelvic nodal metastases. ⁶⁸Ga-PSMA-11 PET studies for the patients who underwent prostatectomy were interpreted by three blinded, independent readers. The primary endpoint — sensitivity and specificity for detection of involved pelvic lymph nodes, compared with histopathology — was 0.40 and 0.95, respectively. Positive and negative predictive values were 0.75 and 0.81, respectively.