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False positive PSMA PET for tumor remnants in the irradiated prostate and other interpretation pitfalls in a prospective multi-center trial
- Fendler, Wolfgang P;
- Calais, Jeremie;
- Eiber, Matthias;
- Simko, Jeffrey P;
- Kurhanewicz, John;
- Santos, Romelyn Delos;
- Feng, Felix Y;
- Reiter, Robert E;
- Rettig, Matthew B;
- Nickols, Nicholas G;
- Kishan, Amar U;
- Slavik, Roger;
- Carroll, Peter R;
- Lawhn-Heath, Courtney;
- Herrmann, Ken;
- Czernin, Johannes;
- Hope, Thomas A
- et al.
Abstract
Purpose
Readers need to be informed about potential pitfalls of [68Ga]Ga-PSMA-11 PET interpretation.Methods
Here we report [68Ga]Ga-PSMA-11 PET findings discordant with the histopathology/composite reference standard in a recently published prospective trial on 635 patients with biochemically recurrent prostate cancer.Results
Consensus reads were false positive in 20 regions of 17/217 (8%) patients with lesion validation. Majority of the false positive interpretations (13 of 20, 65%) occurred in the context of suspected prostate (bed) relapse (T) after radiotherapy (n = 11); other false positive findings were noted for prostate bed post prostatectomy (T, n = 2), pelvic nodes (N, n = 2), or extra pelvic lesions (M, n = 5). Major sources of false positive findings were PSMA-expressing residual adenocarcinoma with marked post-radiotherapy treatment effect. False negative interpretation occurred in 8 regions of 6/79 (8%) patients with histopathology validation, including prostate (bed) (n = 5), pelvic nodes (n = 1), and extra pelvic lesions (n = 2). Lesions were missed mostly due to small metastases or adjacent bladder/urine uptake.Conclusion
[68Ga]Ga-PSMA-11 PET at biochemical recurrence resulted in less than 10% false positive interpretations. Post-radiotherapy prostate uptake was a major source of [68Ga]Ga-PSMA-11 PET false positivity. In few cases, PET correctly detects residual PSMA expression post-radiotherapy, originating however from treated, benign tissue or potentially indolent tumor remnants.Trial registration number
ClinicalTrials.gov Identifiers: NCT02940262 and NCT03353740.Many UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.