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Vienna, Austria

ESTRO 2023

Session Item

Urology
6018
Poster (Digital)
Clinical
MRgSBRT reirradiation in locally recurrent prostate cancer: a multicentric retrospective analysis
Andrea D'Aviero, Italy
PO-1497

Abstract

MRgSBRT reirradiation in locally recurrent prostate cancer: a multicentric retrospective analysis
Authors:

Andrea D'Aviero1, Luca Boldrini2,3, Angela Romano2, Giuditta Chiloiro2, Stefanie Corradini4, Viola De Luca2, Valeria Verusio5, Alessandra Castelluccia6, Anna Rita Alitto2, Francesco Catucci1, Gianmarco Grimaldi6, Christian Trapp7, Juliane Hörner-Rieber8, Domenico Marchesano6, Vincenzo Frascino2, Gian Carlo Mattiucci1,5, Vincenzo Valentini2,5, Piercarlo Gentile6, Maria Antonietta Gambacorta2,5

1Mater Olbia Hospital, Radiation Oncology, Olbia, Italy; 2Fondazione Policlinico Universitario Agostino Gemelli IRCCS, UOC Radioterapia Oncologica, Roma, Italy; 3Università Cattolica del Sacro Cuore, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, , Roma, Italy; 4University Hospital LMU , Department of Radiation Oncology, Munich, Germany; 5Università Cattolica del Sacro Cuore, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Roma, Italy; 6Ospedale San Pietro Fatebenefratelli di Roma, Radiation Oncology, Roma, Italy; 7University Hospital LMU, Department of Radiation Oncology, Munich, Germany; 8Heidelberg University Hospital, Heidelberg Ion-Beam Therapy Center (HIT), Department of Radiation Oncology, Heidelberg, Germany

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Purpose or Objective

The optimal workflow for re-irradiation of Prostate Cancer (PC) local recurrences represents an emerging challenge in the era of advanced local re-treatment modalities. In this context, stereotactic body radiation therapy (SBRT) allows the delivery of curative doses, efficaciously sparing the surrounding OARs. Magnetic Resonance Guided Radiation Therapy (MRgRT) has shown promising results in terms of feasibility and efficacy of delivering SBRT thanks to the enhanced soft tissue contrast and the online adaptive workflow.
This multicentric retrospective analysis evaluates the feasibility and efficacy of PC re-irradiation, using a 0.35 T MR-Linac.

Material and Methods

Patients affected by local recurrences of PC and treated in five european institutions between 2019 and 2022 were retrospectively collected. All patients had undergone a previous long course Radiation Therapy (RT) in definitive or adjuvant setting.
Re-treatment MRgSBRT was delivered with a total dose ranging from 25 to 40 Gy in 5 fractions.
Acute and late toxicity were scored according to CTCAE v 5.0 and treatment response was assessed at the end of the treatment and during follow-up visits.

Results

Eighteen patients were included in the analysis. All the patients had previously undergone External Beams Radiation Therapy (EBRT) with dose ranging from 59.36 to 80 Gy. SBRT re-treatment planning and delivery were performed on hybrid 0.35 T MRI images. Median cumulative Biologically Effective Dose (BED) of SBRT re-treatment was 213,3 Gy (103,1-560), considering an α/β of 1.5.
Median FUP time was 4 months (range 2-30). Complete response was achieved in 4 patients (22.2%). No grade ≥ 2 acute genitourinary (GU) toxicity events were recorded, while gastrointestinal (GI) acute toxicity events occurred in 4 patients (22.2%). Table 1 summarizes 1-year and 2-years percentage for investigated clinical outcomes, Table 2 summarizes acute and late toxicity rates.

Conclusion

This experience encourages to consider MRgSBRT as a valid therapeutic approach for the treatment of clinically relapsed PC. The accurate identification of the target volumes provided by the higher soft tissue contrast of MRI treatment images and the automatic gating delivery allow to safely deliver high doses to the target, reaching promising outcomes.