Elena Moreno-Olmedo, Dan Murray, Ben George, Daniel Ford, Nicola Dallas, Prantik Das, Ami Sabharwal, Yoodhvir Nagar, Jamie Mills, Carla Perna, Yae-eun Suh, Alex Martin, Philip Camilleri
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引用次数: 0
Abstract
Introduction
Stereotactic ablative radiotherapy (SABR) is a salvage option for locally recurrent prostate cancer (LRPC); however, challenges remain. Stereotactic MRguided Adaptive Radiotherapy (SMART) permits daily adaptation, real-time tracking and automated beam gating, allowing critical organ sparing while potentially improving target coverage. Equivalent Dose in 2 Gy fraction (EQD2) calculation allows accurate organs-at-risk (OAR) dose accumulation in re-irradiation.
We report safety and efficacy of daily SMART re-irradiation for LRPC, alongside an EQD2-based OAR tolerance calculation method.
Methods
Salvage SMART to histologically proven non-metastatic hormone-sensitive LRPC was retrospectively analysed. Inclusion criteria included: ≥18 months post-RT, prostate-specific antigen (PSA) ≤ 30 ng/mL, PSA doubling-time > 6 months, International Prostate Symptom Score (IPSS) ≤ 19, prostate ≤ 80 cc and cT1–T3a/b.Reirradiation regimens were 30–35 Gy/5 fractions. Dose-boost and hormone therapy were allowed. Rectal spacer was recommended.
Outcomes included toxicity, local control (LC), biochemical relapse-free survival (bRFS), progression free survival (PFS) and overall survival (OS). EQD2-based workflow to estimate OAR cumulative constraints was reported.
Results
Between 2019 and 2023, nineteen patients underwent salvage-SMART to whole-gland (n = 12), hemi-gland (n = 5) or seminal vesicle (n = 2) at a median 87 months (range 35–587) from first radiotherapy. All 95 delivered fractions underwent online adaptation, meeting all estimated OAR.
With 21 months follow-up, acute grade 2 genitourinary (GU) toxicity was 21 % with no acute ≥ grade 3 GU or ≥ grade 2 gastrointestinal (GI) toxicity observed. Late GU grade 3 toxicity occurred in 3 patients (15.7 %).
OS was 100%; bRFS 73.7%; LC 84.2%; and median-PFS was not reached. One and two-year PFS were 94.7% and 89.4%. One and two-year LC was 100%. Two contralateral intraprostatic failures followed hemi-gland treatment were observed.
Conclusion
Daily adaptive SMART re-irradiation is a feasible, non-invasive salvage option for LRPC, combining high LC with low toxicity. Our experience supports integrating MR- guidance with an individualized EQD2-informed planning.