Researchers Assess the Accuracy of 68Ga-PSMA-11 PET in Localizing Prostate Cancer

Treatment of patients with biochemically recurrent prostate cancer is guided by disease location and extent. Major guidelines recommend computed tomography (CT), magnetic resonance imaging (MRI) and/or bone scintigraphy at biochemical recurrence. However, these guidelines acknowledge limited sensitivity at low prostate-specific antigen (PSA) levels. Novel positron emission tomography (PET) radiotracers promise to overcome this limitation.

Among those available are 68 gallium-labeled ligands of the prostate-specific membrane antigen (PSMA). Many retrospective studies outside of the United States have shown that 68Ga-PSMA-11 improves detection of biochemically recurrent prostate cancer compared with conventional imaging. However, prospective data are lacking.

With this in mind, scientists designed a single-arm prospective trial to assess the accuracy of 68Ga-PSMA-11 PET. To perform the clinical trial, 635 patients with biochemically recurrent prostate cancer were recruited at both UC San Francisco and UCLA. Scientists investigated the positive predictive value (PPV), detection rate, reproducibility, and safety of 68Ga-PSMA-11 PET imaging in these patients. (Read about the methodology in greater detail.) They established high detection rates, positive predictive value, inter-reader reproducibility, and safety. Overall, the primary endpoint was met: 68Ga-PSMA-11 PET demonstrated 84% to 92% positive predictive value at 75% overall detection rate. Findings were published online on March 28, 2019 in JAMA Oncology.

Thomas Hope, MD, associate professor in residence in the Abdominal Imaging and Nuclear Medicine Sections at the UC San Francisco Department of Radiology and Biomedical Imaging was the corresponding author on this study. Co-others from UCSF Radiology include Robert Flavell, MD, PhD, Ashley Mishoe, PharmD and Raven Smith. Other authors from UCSF include Felix Feng, MD and Peter Carroll, MD, MPH (Urology); and Hao Nguyen, MD, PhD and Eric Small, MD (Helen Diller Family Comprehensive Cancer Center). Patients can read about this trial on NCT02940262 and NCT03353740.