Failure patterns by PSMA PET for recurrent prostate cancer after prostatectomy and salvage radiation.

To characterize patterns of failure using prostate-specific membrane antigen positron emission tomography (PSMA PET) after radical prostatectomy (RP) and salvage radiotherapy (SRT).

Patients with rising PSA post-RP+SRT underwent 68Ga-HBED-iPSMA PET/CT on a single-arm, prospective imaging trial (NCTXXXXXXXX). Scans were centrally reviewed with pattern-of-failure analysis by involved site. Positive scans were classified using three failure categories: pelvic nodal, extra-pelvic nodal or distant non-nodal. Associations with failure categories were analyzed using cumulative incidence and generalized logits regression.

We included 133 men who received SRT a median of 20 months post-RP; 56% received SRT to the prostatic fossa alone, while 44% received pelvic SRT. PSMA PET/CT was performed a median of 48 months post-SRT. Overall, 31% of PSMA PET/CT scans were negative, 2% equivocal and 67% had at least one positive site. Scan detection was significantly associated with PSA level prior to PSMA PET/CT. Analysis of 89 positive scans demonstrated pelvic nodal (53%) was the most common relapse and fossa relapse was low (9%). Overall, positive scans were pelvic (n=35, 26%), extra-pelvic nodal (n=26, 20%) or distant non-nodal failure (n=28, 21%), and 70% of positive scans were oligorecurrent. We observed similar cumulative incidence for all failure categories and relatively few clinicodemographic associations. Men treated with pelvic SRT had reduced odds of pelvic failure versus exclusive fossa treatment.

Pelvic, extra-pelvic nodal and distant non-nodal failures occur with similar incidence post-SRT. Regional nodal relapse is relatively common, especially with fossa-only SRT. A high oligorecurrence rate suggests a potentially important role for PSMA-guided focal therapies.

Urology. 2022 Sep 14 [Epub ahead of print]

Brandon S Imber, Elisabeth O'Dwyer, Stephanie Lobaugh, Sean M McBride, Margaret Hopkins, Marisa Kollmeier, Daniel Gorovets, Victoria Brennan, Luke R G Pike, Richard Gewanter, Borys Mychalczak, Zhigang Zhang, Heiko Schöder, Michael J Zelefsky

Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY 10065., Molecular Imaging and Therapeutics, Department of Radiology, Weill Cornell Medical College, New York, NY 10065., Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY 10065., Department of Radiology, Molecular Imaging and Therapy Service, Memorial Sloan Kettering Cancer Center, New York, NY, USA., Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY 10065. Electronic address: .

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