AUA 2022: Restaging PSMA PET/CT is Associated with Improved Oncological Outcome in Men Who Underwent Salvage Radiation Therapy for Biochemically Recurrent Prostate Cancer

( In a moderated poster presentation at the 2022 American Urologic Association Annual Meeting held in New Orleans and virtually, Dr. Meijer presented results of a study examining the clinical implications of restaging prostate-specific membrane antigen (PSMA)-PET/CT at the time of biochemical recurrence following radical prostatectomy.

To date, there is a wealth of literature demonstrating that PSMA-PET/CT at the time of biochemical recurrence (BCR) has superior diagnostic accuracy for the detection of prostate cancer deposits compared to conventional imaging. This has been shown to translate into changes in clinical management. However, the effect on long-term outcomes has yet to be elucidated. These authors hypothesized that, due to the exclusion of patients with metastatic disease on PSMA-PET/CT, patients who undergo local salvage radiation therapy (SRT) after restaging PSMA-PET/CT for BCR may have better oncological outcomes than patients who underwent ‘blind’ SRT without PSMA-PET/CT. Therefore, the aim of this study was to compare the oncological outcome of a patient cohort who underwent PSMA PET-imaging prior to SRT to that of a patient cohort which did not have PSMA PET-imaging before SRT.

The authors included 610 patients who underwent SRT, of whom 298 underwent a PSMA-PET/CT prior to SRT and 312 did not. No patient received additional hormonal therapy with salvage radiotherapy. The authors matched patients who received pre-SRT PSMA-PET/CT to those who did not based on prostate-specific antigen (PSA)-value at initiation of SRT, pathological Grade Group, pathological T-stage, surgical margin status, and biochemical persistence after robotic assisted radical prostatectomy (RARP). The primary outcome was biochemical progression at one year after SRT, defined as either a rise of PSA ≥0.2 ng/mL above the nadir after SRT, or the start of additional treatment.

The authors included 216 matched patients in both cohorts (108 patients per cohort). Among those patients who underwent SRT without PSMA-PET/CT prior to SRT, 23/108 patients (21%) had biochemical progression of disease at one year after SRT, compared to 9/108 patients (8%) who underwent restaging PSMA-PET/CT prior to SRT (p=0.007). 

The authors concluded that patients who underwent restaging PSMA-PET/CT at the time of BCR after RARP had better short-term oncological outcomes after SRT than those who underwent ‘blind’ SRT. However, the validity of this approach requires assessment in a randomized fashion using an intention to treat approach.

Presented by: Dennie Meijer, MD, Amsterdam, Netherlands

Written by: Christopher J.D. Wallis, University of Toronto, Twitter: @WallisCJD during the 2022 American Urological Association (AUA) Annual Meeting, New Orleans, LA, Fri, May 13 – Mon, May 16, 2022.



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