Since the introduction of PSMA PET/CT with 68Ga-PSMA-11, this modality for imaging prostate cancer (PC) has spread worldwide. Preclinical studies have demonstrated that short-term androgen deprivation therapy (ADT) can significantly increase PSMA expression on PC cells. Additionally, retrospective clinical data in large patient cohorts suggest a positive association between ongoing ADT and a pathological PSMA PET/CT scan. The present evaluation was conducted to further analyse the influence of long-term ADT on PSMA PET/CT findings.
A retrospective analysis was performed of all 1,704 patients who underwent a 68Ga-PSMA-11 PET/CT scan at our institution from 2011 to 2017 to detect PC. Of 306 patients scanned at least twice, 10 had started and continued ADT with a continuous clinical response between the two PSMA PET/CT scans. These ten patients were included in the current analysis which compared the tracer uptake intensity and volume of PC lesions on PSMA PET/CT before and during ongoing ADT.
Overall, 31 PC lesions were visible in all ten patients before initiation of ADT. However, during ongoing ADT (duration 42-369 days, median 230 days), only 14 lesions were visible in eight of the ten patients. The average tracer uptake values decreased in 71% and increased in 12.9% of the PC lesions. Of all lesions, 33.3% were still visible in six patients with a complete PSA response (≤0.1 ng/ml).
Continuous long-term ADT significantly reduces the visibility of castration-sensitive PC on PSMA PET/CT. If the objective is visualization of the maximum possible extent of disease, we recommend referring patients for PSMA PET/CT before starting ADT.
European journal of nuclear medicine and molecular imaging. 2018 Jul 07 [Epub ahead of print]
Ali Afshar-Oromieh, Nils Debus, Monika Uhrig, Thomas A Hope, Michael J Evans, Tim Holland-Letz, Frederik L Giesel, Klaus Kopka, Boris Hadaschik, Clemens Kratochwil, Uwe Haberkorn
Department of Nuclear Medicine, Heidelberg University Hospital, Heidelberg, Germany. ., Department of Nuclear Medicine, Heidelberg University Hospital, Heidelberg, Germany., Department of Radiology, German Cancer Research Center, Heidelberg, Germany., Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA., Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, USA., Department of Biostatistics, German Cancer Research Center, Heidelberg, Germany., Division of Radiopharmaceutical Chemistry, German Cancer Research Center, Heidelberg, Germany., Department of Urology, Essen University Hospital, University of Duisburg-Essen, Essen, Germany.