This was a U.S. Federal Drug Administration (FDA) Investigational New Drug Application (IND) approved the study (NCT03368547, NCT02611882, NCT02919111) taking place between December 2015 and August 2019 at the University of California, San Francisco (UCSF) and the University of California, Los Angeles (UCLA), with a total of 633 patients who were imaged. More than 277 patients underwent radical prostatectomy. All patients had intermediate to high-risk prostate cancer according to the D’Amico risk classification.
Patients were injected with a 3-7 mCI of 68Ga-PSMA-11 and imaged with either PET/CT or PET/MRI.
Imaging occurred 50 to 100 minutes after injection (mean of 65 of minutes), with 64% of the patients receiving diuretics as well.
The imaging results were compared to pathology at radical prostatectomy, with three blinded readers being used with no clinical data available to them at the time of interpretation.
The surgery patient population is shown in Table 1, and Table 2 demonstrates the sensitivity and specificity of prostate-specific membrane antigen imaging (PSMA) imaging.
Table 1 – Surgery patient population:
Table 2 – Sensitivity and specificity:
The authors further stratified the sensitivity and specificity by prostate-specific antigen (PSA) and Gleason score, as can be seen in Table 3, showing rising sensitivity with increased PSA and Gleason score.
Table 3: Sensitivity and specificity stratified by PSA and Gleason score:
When specifically assessing patients who underwent radical prostatectomy with pelvic lymph node dissection, if they had lymph nodes measuring 1 centimeter or less-14 patients were true positives, and 34 patients were false negatives resulting in a sensitivity of 0.29. For patients with lymph nodes measuring more than one centimeter, there were 16 true positives and 11 false negatives culminating in a sensitivity of 0.59. Table 4 demonstrates the sensitivity and specificity with regards to positive and negative lymph nodes.
Table 4 – Sensitivity and specificity with regards to lymph nodes removed at surgery:
Dr. Hope continued and mentioned the important result that 87% of patients with true positive disease (20/23) on PSMA positron emission tomography (PET) scan had a biochemical recurrence following radical prostatectomy. A total of 7 patients had an inadequate follow-up to make any determination.
Dr. Hope concluded his talk stating that the results of this prospective trial evaluating 68Ga-PSMA-11 demonstrate a sensitivity of 40% and specificity of 95%. Patients with larger nodes, higher preoperative PSA, and higher Gleason score had increased sensitivities. Lastly, 87% of patients with a true positive disease on PSMA had biochemical recurrence after surgery. Optimal management based on PSMA PET results has yet to be determined.
Presented by: Thomas Hope, MD, Associate Professor, Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
Written by: Hanan Goldberg, MD, MSc., Urology Department, SUNY Upstate Medical University, Syracuse, NY, USA, @GoldbergHanan at the 2020 American Urological Association (AUA) Annual Meeting, Virtual Experience #AUA20, June 27- 28, 2020
Watch: 68Ga-PSMA PET: A Novel Imaging Technique Prior to Radical Prostatectomy in Men with Intermediate or High-Risk Prostate Cancer - Thomas Hope
Read: ASCO 2020: Accuracy of 68Ga-PSMA-11 for Pelvic Nodal Metastasis Detection Prior to Radical Prostatectomy and Pelvic Lymph Node Dissection