False positive PSMA PET for tumor remnants in the irradiated prostate and other interpretation pitfalls in a prospective multi-center trial

• DOI: 10.1007/s00259-020-04945-1
• Publication Date: 2020-08-17T16:04:07Z
• Authors: Wolfgang P. Fendler; Jeremie Calais; Matthias Eiber; Jeffrey P. Simko; John Kurhanewicz; Romelyn Delos Santos; Felix Y. Feng; Robert E. Reiter; Matthew B. Rettig; Nicholas G. Nickols; Amar U. Kishan; ; Okamoto Shozo; Louise Emmett; Helle D. Zacho; Harun Ilhan; Christoph Rischpler; Axel Wetter; Heiko Schoder; Irene A. Burger; Roger Slavik; Peter R. Carroll; Courtney Lawhn-Heath; Ken Herrmann; Johannes Czernin; Thomas A. Hope
• Keywords: Center (category theory)

Readers need to be informed about potential pitfalls of [68Ga]Ga-PSMA-11 PET interpretation.Here we report findings discordant with the histopathology/composite reference standard in a recently published prospective trial on 635 patients biochemically recurrent prostate cancer.Consensus reads were false positive 20 regions 17/217 (8%) lesion validation. Majority interpretations (13 20, 65%) occurred context suspected (bed) relapse (T) after radiotherapy (n = 11); other noted for bed post prostatectomy (T, n 2), pelvic nodes (N, or extra lesions (M, 5). Major sources PSMA-expressing residual adenocarcinoma marked post-radiotherapy treatment effect. False negative interpretation 8 6/79 histopathology validation, including 5), 1), and 2). Lesions missed mostly due small metastases adjacent bladder/urine uptake.[68Ga]Ga-PSMA-11 at biochemical recurrence resulted less than 10% interpretations. Post-radiotherapy uptake was major source positivity. In few cases, correctly detects PSMA expression post-radiotherapy, originating however from treated, benign tissue potentially indolent tumor remnants.ClinicalTrials.gov Identifiers: NCT02940262 NCT03353740.