In case of oligo-recurrent prostate cancer (PC) following prostatectomy, 68Ga-PSMA-PET/CT can be used to detect a specific site of recurrence and to initiate metastasis-directed radiation therapy (MDT). However, large heterogeneities exist concerning doses, treatment fields and radiation techniques, with some studies reporting focal radiotherapy (RT) to PSMA-PET/CT positive lesions only and other studies using elective RT strategies. We aimed to compare oncological outcomes and toxicity between PET/CT-directed RT (PDRT) and PDRT plus elective RT (eRT; i.e. prostate bed, pelvic or paraaortal nodes) in a large retrospective multicenter study.
Data of 394 patients with oligo-recurrent 68Ga-PSMA-PET/CT-positive PC treated between 04/2013 and 01/2018 in six different academic institutions were evaluated. Primary endpoint was biochemical-recurrence-free survival (bRFS). bRFS was analyzed using Kaplan-Meier survival curves and log rank testing. Uni- and multivariate analyses were performed to determine influence of treatment parameters.
In 204 patients (51.8%) RT was directed only to lesions seen on 68Ga-PSMA-PET/CT (PDRT), 190 patients (48.2%) received PDRT plus eRT. PDRT plus eRT was associated with a significantly improved 3-year bRFS compared to PDRT alone (53 vs. 37%; p = 0.001) and remained an independent factor in multivariate analysis (p = 0.006, HR 0.29, 95% CI 0.12-0.68). This effect was more pronounced in the subgroup of patients who were treated with PDRT and elective prostate bed radiotherapy (ePBRT) with a 3-year bRFS of 61% versus 22% (p <0.001). Acute and late toxicity grade ≥3 was 0.8% and 3% after PDRT plus eRT versus no toxicity grade ≥3 after PDRT alone.
In this large cohort of patients with oligo-recurrent prostate cancer, elective irradiation of the pelvic lymphatics and the prostatic bed significantly improved bRFS when added to 68Ga-PSMA-PET/CT-guided focal radiotherapy. These findings need to be evaluated in a randomized controlled trial.
Frontiers in oncology. 2021 May 10*** epublish ***
Simon Kirste, Stephanie G C Kroeze, Christoph Henkenberens, Nina-Sophie Schmidt-Hegemann, Marco M E Vogel, Jessica Becker, Constantinos Zamboglou, Irene Burger, Thorsten Derlin, Peter Bartenstein, Juri Ruf, Christian la Fougère, Matthias Eiber, Hans Christiansen, Stephanie E Combs, Arndt-Christian Müller, Claus Belka, Matthias Guckenberger, Anca-Ligia Grosu
Department of Radiation Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany., Department of Radiation Oncology, University Hospital Zürich, University of Zurich, Zurich, Switzerland., Department of Radiotherapy and Special Oncology, Medical School Hannover, Hannover, Germany., Department of Radiation Oncology, University Hospital LMU Munich, Munich, Germany., Department of Radiation Oncology, Technical University Munich, Munich, Germany., Department of Radiation Oncology, University Hospital Tübingen, Tübingen, Germany., Department of Nuclear Medicine, University Hospital Zürich, University of Zurich, Zurich, Switzerland., Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany., Department of Nuclear Medicine, University Hospital LMU Munich, Munich, Germany., Department of Nuclear Medicine, Medical Center-University of Freiburg, University of Freiburg, Freiburg, Germany., Department of Nuclear Medicine and Clinical Molecular Imaging, University Hospital Tübingen, Tübingen, Germany., Department of Nuclear Medicine, Technical University Munich, Munich, Germany.