A Prospective Study of 18F-DCFPyL PSMA PET/CT Restaging in Recurrent Prostate Cancer following Primary External Beam Radiotherapy or Brachytherapy.

Radio-recurrent prostate cancer is typically detected by a rising PSA and may reflect local or distant disease. PET radiotracers targeting PSMA such as 18F-DCFPyL have shown promise in restaging men with recurrent disease post-prostatectomy but are less well characterized in the setting of radio-recurrent disease.

A prospective, multi-institutional study was conducted to evaluate the impact of 18F-DCFPyL PET/CT when added to diagnostic imaging (DI; CT abdomen and pelvis, bone scan, mpMRI pelvis) for men with radio-recurrent prostate cancer. All men were imaged with DI and subsequently underwent 18F-DCFPyL PET/CT with local and central reads. Tie break reads were performed as required. Management questionnaires were completed after DI and again after 18F-DCFPyL PET/CT. Discordance in patterns of disease detected with 18F-DCFPyL PET/CT versus DI and changes in management were characterized.

Seventy-nine men completed the study. Most men had T1 disease (62%) and Gleason score <7 (95%). Median PSA at diagnosis was 7.4ng/ml and at relapse was 4.8ng/ml. DI detected isolated intra-prostatic recurrence in 38/79 men (48%), regional nodal recurrence in 9/79 (11%), distant disease in 12/79 (15%), and no disease in 26/79 (33%). 18F-DCFPyL PET/CT detected isolated intra-prostatic recurrence in 38/79 men (48%), regional nodal recurrence in 21/79 (27%), distant disease in 24/79 (30%), and no disease in 10/79 (13%). DI identified 8/79 (10%) patients to have oligometastatic disease, compared to 21/79 (27%) with 18F-DCFPyL PET/CT. 18F-DCFPyL PET/CT changed proposed management in 34/79 (43%) patients.

18F-DCFPyL PET/CT identified extra-prostatic disease in twice as many men with radio-recurrent prostate cancer compared with DI and detected a site of recurrence in 87% of men compared to 67% with DI. Further, 18F-DCFPyL PET/CT identified potentially actionable disease (prostate only-recurrence or oligometastatic disease) in 75% of men and changed proposed management in 43% of men.

International journal of radiation oncology, biology, physics. 2019 Nov 12 [Epub ahead of print]

Wei Liu, Katherine Zukotynski, Louise Emmett, Hans T Chung, Peter Chung, Robert Wolfson, Irina Rachinsky, Anil Kapoor, Ur Metser, Andrew Loblaw, Gerard Morton, Tracy Sexton, Michael Lock, Joelle Helou, Alejandro Berlin, Colm Boylan, Susan Archer, Greg Pond, Glenn Bauman

London Health Sciences Centre, London, Canada., McMaster University, Hamilton, Canada., St. Vincent's Hospital, Sydney, Australia., Sunnybrook Health Sciences Centre, Toronto, Canada., Princess Margaret Cancer Centre, Toronto, Canada., St. Joseph's Healthcare, Hamilton Canada., London Health Sciences Centre, London, Canada. Electronic address: .

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