ESTRO 2023 - Abstract Book

S1296

Digital Posters

ESTRO 2023

Fig. 1: LRFS after spine SBRT for bone metastases.

Fig. 2: DMFS in the single fx vs 3-5 fx treatments.

Conclusion Spine SBRT appears clinically feasible and safe, allowing the delivery of ablative/radical doses to the target, while sparing the critical organs-at-risk, namely the critical neural tissues with good local control and low toxicity. In our experience, a trend to a better DMFS was obtained with a single fx vs 3-5 fx in the two fractionation groups, with similar disease burden.

PO-1596 Stereotactic body re-irradiation for bone metastases

L. Giannini 1,2 , F. Ferrario 1,2 , M. Torrisi 1,2 , C. Chissotti 1,2 , C.L. Deantoni 1 , S. Broggi 3 , L. Perna 3 , C. Fiorino 3 , M. Midulla 4,2 , S.L. Villa 1,2 , I. Dell'Oca 1 , A. Fodor 1 , A. Del Vecchio 3 , S. Arcangeli 5,2 , N.G. Di Muzio 1,6 1 IRCCS San Raffaele Scientific Institute, Department of Radiation Oncology, Milan, Italy; 2 Università degli Studi di Milano Bicocca, School of Radiation Oncology, Milan, Italy; 3 IRCCS San Raffaele Scientific Institute, Medical Physics, Milan, Italy; 4 IRCCS San Raffaele Scientific Institute, Department of Radiation Oncology, Milan, Italy; 5 San Gerardo Hospital, Department of Radiation Oncology, Monza, Italy; 6 Vita-Salute San Raffaele University, School of Medicine and Surgery, Milan, Italy Purpose or Objective The significant increase in survival of metastatic patients with target therapies has highlighted the problem of relapses of bone metastases treated with palliative and radical dosages. The aim of this study is to report our experience with the use of SBRT for the retreatment of bone metastases, evaluating efficacy and toxicity. Materials and Methods In this retrospective study, 29 re-irradiations delivered between January 2018 and March 2021 in 25 pts with radiological evidence of bone relapse were analyzed. Metastatic sites were: one cervical spine, 6 thoracic spine, 12 lumbar spine, 2 sacrum, 6 hip, one rib and one skull. Previous RT on the same volume was performed with conventional external beam radiation therapy (cEBRT) for 24 treatments, and with SBRT for 5 treatments. Median age was 72 (37-89) years at the time of the SBRT. Primary tumor was prostate in 18 pts, lung in 3 pts, breast in 2 pts, kidney in one patient and endometrium in one patient. Median interval from previous radical/palliative external beam RT was 63 (7-223) months. SBRT was delivered with CyberKnife® (Accuray, Sunnyvale, CA, USA) real-time tracking radiation therapy. Median prescribed dose was 25 (12-30) Gy, to the median isodose of 80 (69-82)%, in 1-5 fractions. Fifteen pts were treated with precautional steroid therapy at the time of re-RT. Toxicity was assessed with CTCAE version 5.0.

Results