ESTRO 2023 - Abstract Book

S1281

Digital Posters

ESTRO 2023

Conclusion We considered 5 valid metrics to provide data for quality improvement in palliative radiation. While our work may contribute to guide clinical decision making in palliative RT, further research in other centres is necessary considering there is still relatively little work on assessing quality and outcomes at scale despite the widespread usage of RT.

PO-1578 Sbrt boost following prior rt: toxicity results from a phase I dose escalation study (Destroy-1)

D. Pezzulla 1 , G. Macchia 1 , M. Ferro 1,1 , S. Cilla 2 , M. Buwenge 3 , C. Romano 2 , S. Cammelli 4,5 , P. Bonome 1 , V. Picardi 1 , M.A. Gambacorta 6,7 , A.G. Morganti 3,8 , F. Deodato 9,1 1 Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Radiation Oncology Unit, Campobasso, Italy; 2 Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Medical Physics Unit, Campobasso, Italy; 3 IRCCS Azienda Ospedaliero-Universitaria di Bologna, Radiation Oncology, Bologna, Italy; 4 IRCCS Azienda Ospedaliero-Universitaria di Bologna, Radiation Oncology, Bologna, Italy; 5 Alma Mater Studiorum Bologna University, Department of Experimental, Diagnostic, and Specialty Medicine - DIMES, Bologna, Italy; 6 Fondazione Policlinico Universitario A Gemelli IRCCS, UOC di Radioterapia Oncologica, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia , Roma, Italy; 7 Università Cattolica del Sacro Cuore, Istituto di Radiologia, Roma, Italy; 8 Alma Mater Studiorum Bologna University, Department of Experimental, Diagnostic, and Specialty Medicine - DIMES, Bologna, Italy; 9 Università Cattolica del Sacro Cuore, Istituto di Radiologia, Roma, Italy Purpose or Objective To report the toxicity profile of a dose escalation study (Destroy-1) investigating stereotactic radiotherapy (SBRT) boost administered within 4 months after a previous in-field radiotherapy (RT). Materials and Methods In the frame of Destroy-1 trial, a phase I dose-escalation multiarm stereotactic radiotherapy (SBRT) clinical study, two arms (f) and (g) were conceived for studying the optimal dose of a stereotactic boost following prior in-field RT. The 2 arms were differentiated as follows: patients receiving a boost after a prior RT dose ≤ 50 Gy (arm f) or after a prior RT dose >50 Gy (arm g); moreover, the total dose was escalated up to 35 Gy (arm f) or 30 Gy (arm g) through 3 levels, respectively (Table 1). Each cohort was evaluated for dose-limiting toxicity (DLT) and consisted of 6 patients; if one of the patients experienced a DLT, the cohort was expanded to 12 patients. DLT was defined as any radiation-related > Grade 3 toxicity (RTOG criteria) occurring within 6 months from SBRT. Adverse events occurring later than 6 months after SBRT were described as late toxicities, but were not considered in DLT evaluation. Results 69 lesions (41 lesions in the (f) arm and 28 in the (g) arm) accounting for 57 consecutive patients (M/F: 30/27; median age: 66 years; range 43-84) were treated from July 2005 to April 2018. About 96.5% of the patients had an ECOG performance status between 0 and 1, with the most common comorbidity being coronary disease (80.6%). Most patients had a primary lung (28.1%) and breast cancer (12.3%). The most common boost sites were the pelvis (34.8%) and thorax (52.2), with the majority of the lesions being nodal ones (52.2%). The median GTV was 9.5cc (0.1-99.7) and the median PTV was 26.8cc (1.5-281.2). No acute toxicity above G2 was recorded, while only two late toxicities > G2 were recorded: one G3 intestinal bleeding and one G3 bowel stenosis. More details on dose-level accrual and toxicity profile are shown in Table 1. Local control at 1-, 2- and 5-years was 93.0%, 760% and 67.1% respectively.