68Ga-PSMA-11 PET/CT-Guided Stereotactic Body Radiation Therapy Retreatment in Prostate Cancer Patients with PSA Failure after Salvage Radiotherapy.

Paola Caroli,Valentina Di Iorio,Anna Sarnelli,Monica Celli,Manuela Monti,Ugo De Giorgi,Giulia Ghigi,Antonino Romeo,Federica Matteucci,Emanuela Scarpi,Giovanni Paganelli,Sarah Pia Colangione

doi:10.3390/biomedicines8120536

Abstract

(1) Purpose: To investigate the role of 68Ga-PSMA-11 PET/CT in guiding retreatment stereotactic body radiation therapy (SBRT) in prostate cancer (PCa) patients in biochemical recurrence (BCR) after salvage radiotherapy (S-RT). (2) Methods: We retrospectively evaluated PCa patients previously treated with S-RT on the prostate bed and with proven serum prostate antigen (PSA) failure after S-RT. In all patients (pts), 68Ga-PSMA-11 PET/CT was positive in the prostate bed only and guided retreatment SBRT. All retreatments were performed by applying the same radiotherapy protocol (median dose of 18 Gy/3 fractions; IQR 18–21 Gy). The median follow-up was 27 months (range 4–35 months). (3) Results: 38 consecutive patients were considered in this analysis. The overall median PSA level before RT was 1.10 ng/mL (IQR 0.82–2.59). PSA decreased at 3 and 6 months after treatment, with a median value of 0.60 ng/mL (IQR 0.31–0.96; p < 0.001) and 0.51 ng/mL (IQR 0.29–1.17; p < 0.001), respectively. Overall, biochemical recurrence-free survival (b-RFS) was 15.0 months (95% CI 13–23). Grade-1 toxicity was reported in 31.6% of patients (12/38). (4) Conclusion: These results confirm that 68Ga-PSMA-11-PET/CT is able to identify the site of recurrence in patients who have failed S-RT, thus supporting the use of metastases-directed radiotherapy as a safe and effective treatment.

Highlights

Prostate cancer (PCa) is the most frequent malignancy in male patients [1]
The aim of this study is to investigate the role of 68 Ga-PSMA-11 PET/CT in guiding retreatment (SBRT) in prostate cancer (PCa) patients affected by prostate antigen (PSA) failure after salvage radiotherapy (S-RT)
76 consecutive postsalvage biochemical recurrence (BCR) patients sent by the radiotherapy unit to perform 68 Ga-PSMA-11

Summary

Introduction

Prostate cancer (PCa) is the most frequent malignancy in male patients [1]. Despite radical approaches such as prostatectomy and radiation therapy, 20–30% of PCa patients will develop a biochemical relapse (BCR) within 10 years from primary care, defined by progressively rising serum prostate antigen (PSA) levels [2]. Salvage radiation therapy to the prostatic bed and/or pelvic nodes can offer a chance for disease control at first BCR. Many patients treated with standard salvage radiation therapy experience PSA failure as a result of new recurrences of active disease; the mainstay for disease control in such patients is systemic therapy based on hormone blockade. In early BCR scenarios, namely, for serum PSA levels as low as 1.0 ng/mL, patients may harbor low burden disease within the pelvis and/or at a few extrapelvic sites, deemed to be treatable with local therapy when the site of recurrence is localized [4]

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