Combining 68Ga-PSMA-PET/CT-Directed and Elective Radiation Therapy Improves Outcome in Oligorecurrent Prostate Cancer: A Retrospective Multicenter Study

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

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10 Scopus citations

Abstract

Background: 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. Methods: 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. Results: 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. Conclusions: 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.

Original languageEnglish
Article number640467
JournalFrontiers in Oncology
Volume11
DOIs
StatePublished - 10 May 2021

Keywords

  • elective nodal radiotherapy
  • elective prostate bed radiotherapy
  • metastasis-directed radiotherapy
  • oligorecurrent
  • prostate cancer
  • radiotherapy

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