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Objective To assess European Association of Urology (EAU) risk groups for biochemical recurrence (BCR) of prostate cancer relative to prostate-specific membrane antigen-positron emission tomography (PSMA-PET) status and oncological outcomes. Patients and Methods A retrospective analysis of a study that incorporated PSMA-PET for men with BCR after radical prostatectomy (RP) was undertaken. EAU risk groups were considered relative to clinical variables, PSMA-PET findings, and deployment of salvage radiotherapy (SRT). The primary oncological outcome was event-free survival (EFS) and this was analysed relative to clinical and imaging variables. An 'event' occurred if prostate-specific antigen (PSA) level rose >0.2 ng/mL above nadir or additional therapies were introduced. Results A total of 137 patients were included, most of whom had EAU high-risk disease (76%) and/or low PSA levels (80% <0.5 ng/mL) at the time of PSMA-PET. EAU risk group was not associated with regional nodal/distant metastasis on PSMA-PET. Regional nodal/distant metastasis on PSMA PET (compared to negative/local recurrence: hazard ratio [HR] 2.2; P = 0.002) and SRT use (vs no SRT: HR 0.44; P = 0.004) were associated with EFS. EAU high-risk status was not significantly associated with worse EFS (HR 1.7, P = 0.12) compared to EAU low-risk status. Among patients who received SRT, both regional/distant metastasis on PSMA-PET (HR 3.1; P < 0.001) and EAU high-risk status (HR 2.9; P = 0.04) were independently associated with worse EFS, which was driven by patients in the EAU high-risk group with regional/distant metastases (38%; HR 3.1, P = 0.001). Conclusions In patients with post-RP BCR, PSMA-PET findings and receipt of SRT predicted EFS. In patients receiving SRT, PSMA status combined with EAU risk grouping was most predictive of EFS. These findings suggest that the EAU risk groups could be improved with the addition of PSMA-PET. [ABSTRACT FROM AUTHOR]

68 Ga-labeled prostate-specific membrane antigen (PSMA) PET/CT is increasingly used in men with biochemical recurrence (BCR) after radical prostatectomy (RP), but its longer-term prognostic or predictive potential in these men is unknown. The aim of this study was to evaluate the predictive value of PSMA PET for a 3-y freedom from progression (FFP) in men with BCR after RP undergoing salvage radiotherapy (sRT). Methods: This prospective multicenter study enrolled 260 men between 2015 and 2017. Eligible patients were referred for PSMA PET with a rising level of prostate-specific antigen (PSA) after RP. Management after PSMA PET was recorded but not mandated. PSMA PET protocols were standardized across sites and reported prospectively. Clinical, pathologic, and surgical information; sRT; timing and duration of androgen deprivation; 3-y PSA results; and clinical events were documented. FFP was defined as a PSA rise of no more than 0.2 ng/mL above nadir after sRT, with no additional treatment. Results: The median PSA was 0.26 ng/mL (interquartile range, 0.15-0.59 ng/mL), and follow-up was 38 mo (interquartile range, 31-43 mo). PSMA PET had negative results in 34.6% (90/260), showed disease confined to the prostatic fossa in 21.5% (56/260), showed disease in the pelvic nodes in 26.2% (68/260), and showed distant disease in 17.7% (46/260). Of the patients, 71.5% (186/260) received sRT: 38.2% (71/186) to the fossa only, 49.4% (92/186) to the fossa plus the pelvic nodes, and 12.4% (23/186) to the nodes alone or stereotactic body radiation therapy. PSMA PET was highly predictive of FFP at 3 y after sRT. Overall, FFP was achieved in 64.5% (120/186) of those who received sRT, 81% (81/100) with negative results or fossa-confined findings versus 45% (39/86) with extrafossa disease ( P < 0.0001). On logistic regression, PSMA PET was more independently predictive of FFP than established clinical predictors, including PSA, T stage, surgical margin status, or Gleason score ( P < 0.002). Thirty-two percent of men with a negative PSMA PET result did not receive treatment. Of these, 66% (19/29) progressed, with a mean rise in PSA of 1.59 ng/mL over the 3 y. Conclusion: PSMA PET results are highly predictive of FFP at 3 y in men undergoing sRT for BCR after RP. In particular, men with negative PSMA PET results or disease identified as still confined to the prostatic fossa demonstrate high FFP, despite receiving less extensive radiotherapy and lower rates of additional androgen deprivation therapy than those with extrafossa disease., (© 2020 by the Society of Nuclear Medicine and Molecular Imaging.)