ESTRO 2023

Session Item

Mixed sites/palliation

Session Code: 6026

Session Type: Poster (Digital)

Track: Clinical

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

Donato Pezzulla, Italy

Presentation Number: PO-1578

Abstract

Abstract Title:

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

Authors:

Donato Pezzulla¹, Gabriella Macchia¹, Milena Ferro¹, Savino Cilla², Milly Buwenge³, Carmela Romano², Marica Ferro¹, Silvia Cammelli^4,5, Paolo Bonome¹, Vincenzo Picardi¹, Maria Antonietta Gambacorta^6,7, Alessio Giuseppe Morganti^3,8, Francesco Deodato^9,1

¹Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Radiation Oncology Unit, Campobasso, Italy; ²Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Medical Physics Unit, Campobasso, Italy; ³IRCCS Azienda Ospedaliero-Universitaria di Bologna, Radiation Oncology, Bologna, Italy; ⁴IRCCS 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; ⁶Fondazione Policlinico Universitario A Gemelli IRCCS, UOC di Radioterapia Oncologica, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia , Roma, Italy; ⁷Università Cattolica del Sacro Cuore, Istituto di Radiologia, Roma, Italy; ⁸Alma Mater Studiorum Bologna University, Department of Experimental, Diagnostic, and Specialty Medicine - DIMES, Bologna, Italy; ⁹Università Cattolica del Sacro Cuore, Istituto di Radiologia, Roma, Italy

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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).

Material 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.

Conclusion

Stereotactic boost within 4 months after previous radiotherapy seems to be feasible with a safe toxicity profile. The end of the study is awaited in order to draw definite conclusions about the safety and efficacy of SBRT boost.