ESTRO 2020 Abstract book

S307 ESTRO 2020

immune cells (neutrophils, macrophages). The late phase (from 12 weeks) is characterized by chronic inflammation and the accumulation of cells in the lung parenchyma such as lymphocytes, macrophages and myofibroblasts secreting extracellular matrix leading to RIPF (4 months to years)(Wynn 2011; Chen et al. 2018). Thus, we will analyze the modification of immune system response focusing on lymphocytes Th1/Th2 and macrophages (M1/M2), and the different changes occurring in lung parenchyma such as endothelial and epithelial apoptosis, myofibroblasts accumulation and collagen deposition. For that, we will perform immune cells analysis by flow cytometry, western blot and immunohistochemistry to analyze modifications in lung parenchyma, and Sirius red to quantify collagen deposition. Cytokines secretion will be assessed using cytokine array focusing mainly on TGFband Th2 cytokine signatures known to mediate pro-fibrotic effects. All those experiments will be done at short (3, 7, 15, 30 days) and late (12, 20 weeks) times after irradiation in both lung interstitium lysats and broncho-alveolal lavages and on lung sections for histological analysis from irradiated mice injected or not with Muse cells. PH-0521 Paravertebral Muscle Training in Patients with Unstable Spinal Metastases T. Sprave 1 1 Universitaetsklinik Freiburg, RadioOncology, Freiburg, Germany Purpose or Objective Isometric paravertebral muscle training (IPMT) may improve mobility, pain, and quality of life (QOL) in cancer patients with spinal metastases. However, this regimen remains unproven in patients with unstable spinal metastases (USM), a population at high risk for clinical exacerbation with such interventions. Thus, we conducted this exploratory, non-blinded, randomized controlled trial (NCT02847754) to evaluate the safety/feasibility of IPMT and secondarily assess pain, bone density, pathologic All patients had histologically/radiologically confirmed USM (per Taneichi score) and underwent non-operative management with 5-10 fractions of palliative radiotherapy (RT). Randomization (1:1) groups were IPMT (intervention, INT) or muscle relaxation (control, CON); both lasted 15 minutes/day and started concurrently with radiotherapy. The primary endpoint was feasibility (completion of training programs 3 months post-RT). Secondary endpoints were pain response (Visual Analog Scale) and opioid consumption, bone density and pathologic fracture rate, and QOL (EORTC questionnaires). Results Sixty patients were randomized and 56 received protocol therapy. Mean survival in both groups was 4.4 months. There were no adverse events with either training regimen. Altogether, ≥80% of the planned sessions were completed by 55% (n=16/29) in CON and 67% (n=18/27) in INT. Regarding the post-radiotherapy home-based training, ≥80% of planned sessions were completed by 64% (n=9/14) of the INT cohort. There were no differences in pain scores, opioid consumption, or bone density between arms (p>0.05 for all). No difference was observed between groups regarding new pathological fractures (INT: n=1 vs fracture rate, and QOL. Material and Methods Poster Highlights: Poster highlights 17 CL : Palliation

CON: n=3) after 3 months (p=0.419).There were no QOL differences between arms (all parameters p>0.05). Conclusion IPMT is safe and feasible for high-risk USM patients. Future trials adequately powered for relevant endpoints are thus recommended. PH-0522 Fractionation and early mortality in palliative radiotherapy across the English NHS K. Spencer 1 , P. Hall 2 , A. Henry 3 , G. Velikova 3 , S. Whalley 4 , R. Birch 4 , K. Le Calvez 5 , M. Williams 6 , E. Morris 4 1 University of Leeds, Leeds Institute of Health Sciences, Leeds, United Kingdom ; 2 Edinburgh University, Edinburgh Cancer Research Centre, Edinburgh, United Kingdom ; 3 University of Leeds, Leeds Institute of Medical Research, Leeds, United Kingdom ; 4 University of Leeds, Leeds Institute of Data Analytics, Leeds, United Kingdom ; 5 Imperial College Healthcare NHS Trust, Radiotherapy department, Leeds, United Kingdom ; 6 Imperial College, Department of Surgery and Cancer, London, United Kingdom Purpose or Objective Hypofractionated palliative radiotherapy (PallRT) aims to improve symptom control and, in limited circumstances, survival whilst minimising treatment burden. Anecdotally, wide variation in use persists. The national radiotherapy dataset (RTDS), collected by PHE, provides a unique opportunity to assess variation in use and early mortality (a marker of futility) following palliative radiotherapy. Material and Methods All radiotherapy episodes delivered 2 years in the English NHS were extracted from the RTDS, linked to cancer registration and admissions data. Treatment intent was defined using clinically determined algorithms. Site- treated using PallRT was defined using anatomical codes. Variation in fractionation patterns of PallRT was assessed by provider organisation. 30 day mortality (30DM) was determined and predictors of 30DM assessed using multi- variable logistic regression models. Variation in 30DM between providers was presented using unadjusted and adjusted funnel plots. Results Over 100,000 palliative radiotherapy treatments were delivered across the English NHS in 2014-15. Treatment to bone lesions accounted for the largest proportion (41.7% of delivered prescriptions), followed by treatments for soft tissue (39.5%), brain and base of skull metastases (10.5%) and the head and neck (2.9%). The fractionation patterns delivered varied widely between provider organisations. For example, 65% of non-emergency bone and spinal treatments were delivered using a single fraction (range 37.7-90.3%), see figure 1. Over 8000 patients died within 30 days of a first treatment episode in the cohort (10.4%). Multiple factors were significantly associated with 30DM. These included fractionation pattern (10 fractions vs single fraction OR 0.23 (95%CI 0.21-0.26)), travel time (>60 minutes vs <20 minutes OR 0.85(95%CI 0.76-0.96)), urgency of treatment (emergency vs routine OR 2.02 (95%CI 1.87- 2.18)) and inpatient status at treatment (inpatient vs outpatient OR 2.44 (95% CI 2.16-2.77)). The variation in 30DM was presented using unadjusted and adjusted funnel plots (see figure 2).