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Objective: To assess topographic concordance between the histopathological features of patients' radical prostatectomy (RP) specimens and the location of the prostate‐specific membrane antigen positron emission tomography (PSMA PET) local recurrences, qualitatively and quantitatively. Patients and Methods: Our cohort was selected from the 100 men who received a 18F‐DCFPyL PET scan in the IMPPORT trial (Australian New Zealand Clinical Trials Registry Number: ACTRN12618001530213), a prospective non‐randomised study completed by GenesisCare Victoria. Eligibility included patients with a rising prostate‐specific antigen (PSA) level (>0.2 ng/mL) after RP and PSMA PET detected local recurrence. Histopathological parameters collated included the location of tumour, extraprostatic extension (EPE), and positive margins. Criteria for the location and 'concordance' between histopathological features and local recurrences were pre‐defined. Results: A total of 24 patients were eligible; the median age was 71 years, the median PSA level was 0.37 ng/mL, and the time between RP and PSMA PET was 2.6 years. In all, 15 patients had recurrences within the vesicourethral anastomotic region and nine within the lateral surgical margins. There was 100% concordance in the left–right plane between tumour location and local recurrence, with 79% of these lesions concordant three‐dimensionally; across craniocaudal, left–right, and anterior–posterior planes. In all, 10 of the 16 (63%) patients with EPE and five of the nine patients with positive margins had three‐dimensional concordance between their pathology and their local recurrence. In quantitative assessment, 17 of the 24 patients, had local recurrences that correlated with the location of their original tumour in the craniocaudal plane. Conclusion: Local recurrence is highly concordant with the position of the tumour within the prostate. Predicting the location of local recurrence using the location of the EPE and positive margins is less helpful. Further investigation into this field, could impact surgical technique and salvage radiotherapy clinical target volume. [ABSTRACT FROM AUTHOR]

Objectives: To assess the correlation of pathological radical prostatectomy (RP) specimen features and prostate‐specific antigen (PSA) characteristics to imaging findings on subsequent 18F‐DCFPyL positron emission tomography/computed tomography (PET/CT) in patients with biochemical failure (BF). Patients and Methods: Retrospective analysis of combined 18F‐DCFPyL PET/CT database of patients from centres in Australia and New Zealand was performed. A total of 205 patients presenting with BF after RP were included in this study. Imaging findings on 18F‐DCFPyL PET/CT were recorded and correlated with the PSA characteristics at BF and pathological features of the original tumour. Results: Of the 205 patients, 120 (58.5%) had evidence of abnormal prostate‐specific membrane antigen (PSMA) expression compatible with recurrent prostate cancer. Increasing PSA velocity (P = 0.01), International Society of Urological Pathology (ISUP) Grade Group (P = 0.02), lymphovascular invasion (P = 0.05) and nodal positivity (P = 0.02) at the time of RP were more likely to demonstrate PSMA positivity. Multivariable logistic regression revealed a higher PSA level prior to PSMA PET/CT (P < 0.01), adjuvant radiotherapy (P = 0.09), Gleason score ≥8 (P < 0.01) and nodal positivity (P = 0.05) were all predictive of PSMA positivity. Conclusion: 18F‐DCFPyL PET/CT positivity, both generally and site specific, correlates with PSA and RP pathological factors. Our results echo cohorts focussing on post‐RP patients, those imaged with 68Ga‐PSMA and those concerning biochemical persistence. Nomograms that include risk factors for 'PSMA‐positive recurrence' in the BF population may increase the catchment of patients with disease confined to the prostate bed or pelvis who have a greater probability of prolonged disease‐free survival. [ABSTRACT FROM AUTHOR]