EAU 2021: Identification of the Best Candidates for PSMA PET/CT Among Patients Experiencing Biochemical Recurrence After Radical Prostatectomy: A New Tool to Optimize of Patient Selection

(UroToday.com) Dr. Giorgio Gandaglia discussed the identification of the best candidates for PSMA PET/CT among those experiencing a biochemical recurrence after radical prostatectomy at the European Association of Urology (EAU) 2021 annual meeting’s detection of recurrence and salvage treatment options after primary treatment of prostate cancer session. Although PSMA PET/CT is recommended in the biochemical recurrence setting after radical prostatectomy, its impact on clinical management is unclear. This is particularly true when considering prostate cancer patients at low risk of metastases who could be managed with salvage radiotherapy alone. The objective of this study was to assess when PSMA PET/CT could be safely avoided or postponed.


There were 182 patients evaluated for this study with PSMA PET/CT for biochemical recurrence after radical prostatectomy between 2016 and 2020. The outcome was distant metastasis (i.e., retroperitoneal, skeletal, or visceral) at PSMA PET/CT. MVA analyses assessed predictors of distant lesions (pathological stage, grade group, salvage radiotherapy, and concomitant ADT). The model based on the regression coefficients was internally validated. An interaction analysis tested whether the association between PSA at PET/CT and distant lesions varied according to the risk calculated using the model. Patients were stratified according to the model-derived risk (<30 vs. ≥30%) and the rate of distant lesions at PET/CT was plotted against PSA values.

Median PSA at PET/CT scan was 0.7 ng/ml. Overall, 76 (41.5%) and 57 (31.1%) had grade group (GG) 4-5 and SVI disease, respectively. Overall, 60 (32.8%) and 24 (13.1%) patients received salvage radiotherapy and ADT before PSMA PET/CT, respectively. Overall, 59 (32.2%) patients had distant spots at PSMA PET/CT. Concomitant ADT (HR 5.5; p=0.02), SVI (HR 3.5; p=0.005) and GG 4-5 (HR 3.7; p=0.01) predicted distant lesions at PET/CT with an AUC of 80%. The rate of distant positive lesions in men with a GG 1-3, no SVI, and no ADT (n=34, 18.6%) was 12%. This increased to 41% in patients with adverse factors (p<0.001). The impact of PSA values at PSMA PET/CT varied according to the novel risk score (p=0.03 by interaction test). While in men with a calculated risk of <30% increasing PSA values at PSMA PET/CT did not impact the risk of distant metastases at PSMA PET/CT, in those with worse characteristics it increased according to PSA levels. As follows is the probability of PSMA positivity according to PSA value at PSMA:

Gandaglia.jpg 

Dr. Gandaglia concluded his presentation with the following take-home messages:

  • Pathological characteristics and previous salvage therapies should identify men more likely to harbor distant metastases at PSMA PET/CT
  • The use of PET/CT can be safely avoided or postponed in individuals with grade group 1-3, no SVI, and who did not receive previous salvage therapies
  • These patients can be considered candidates to salvage radiotherapy without a previous PSMA PET/CT 

Presented by: Giorgio Gandaglia, MD, IRCCS Ospedale San Raffaele, Vita-Salute San Raffaele University, Division of Oncology, Unit of Urology, Milan, Italy

Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, @zklaassen_md on Twitter during the 2021 European Association of Urology, EAU 2021- Virtual Meeting, July 8-12, 2021.

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