ESTRO 2024 - Abstract Book

S1995

Clinical - Mixed sites, palliation

ESTRO 2024

4. Chen, D. et al. Absolute Lymphocyte Count Predicts Abscopal Responses and Outcomes in Patients Receiving Combined Immunotherapy and Radiation Therapy: Analysis of 3 Phase 1/2 Trials. Int. J. Radiat. Oncol. Biol. Phys. 108, 196 – 203 (2020).

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SABR with or without simultaneous integrated dose boost in spinal bone oligometastases

Edoardo Pastorello 1 , Luca Nicosia 1 , Niccolò Giaj-Levra 1 , Rosario Mazzola 1 , Francesco Ricchetti 1 , Michele Rigo 1 , Andrea Gaetano Allegra 1 , Filippo Alongi 1,2 1 IRCCS Sacro Cuore Don Calabria, Advanced Radiation Oncology, Negrar di Valpolicella, Italy. 2 Università degli Studi di Brescia, Radiation Oncology, Brescia, Italy

Purpose/Objective:

Spinal metastases develop in almost one third of cancer patients. Considering the association with pain and in several cases neurological symptoms, spinal metastases can affect quality of life. Stereotactic body radiation therapy (SBRT) is a well established technique for treating oligometastatic patients. Even if radiotherapy has a consolidate symptomatic role in spinal bone metastases using palliative doses, few data are available on its use with ablative doses. The aim of our study is to evaluate efficacy, toxicity and pattern of progression in spinal oligometastatic patients treated with SBRT.

Material/Methods:

We treated a series of spinal oligometastatic patients in our departement between May 2018 and December 2022. Clinical target volume was defined according to Cox criteria for spinal metastases. The primary end-point was local control (LC). Secondary objectives were toxicity, distant progression free survival (DPFS), overall survival (OS) and pattern of relapse (sequential oligometastatic disease (SOMD) versus polimetastatic disease (PMD)). The following covariates were evaluated: primary tumor hystology, biologically effective dose (BED), dose boost to the macroscopic disease, and number of metastases.

Results:

One hundred-thirteen spinal oligometastases in 81 patients were treated. Primary hystology was: prostate (52), breast (21), lung (4), others (4). Median dose was 21 Gy (12-30) delivered in 1 to 5 fractions. Median follow-up was 17 months (range 6 – 47). Dose boost to the macroscopic lesion up to 27 Gy was administered with simultaneous integrated boost techniques in 41 metastases (36.3%). Most of lesions (86) were oligorecurrent metastases. One-, and 2-year LC was 93.3% and 88.8%. Moreover, dose boost to macroscopic lesion did resulted in a significantly improved 2-year LC (100% versus 86%; p= 0.03). At the last follow-up 8 (7%) metastases locally relapsed. Two patients were surgically treated with laminectomy due to local progression, and vertebroplasty after a traumatic