ESTRO 38 Abstract book

S877 ESTRO 38

stabilization in case of spinal instability or neurological deficit. Patients with a life expectancy less than 3 months are deemed unfit for surgery because quality of life is considered to be hampered too much by surgery and revalidation to justify the procedure. Therefore, adequate assessment of expected survival is necessary. The aim of this study was to evaluate whether abdominal fat and muscle distribution, and muscle attenuance are associated Within the UMC Utrecht PRospective Evaluation of interventional StudiEs on boNe meTastases (PRESENT) cohort, we identified all 310 patients who received radiotherapy for thoracic or lumbar spinal metastases. Using an in-house developed delineation tool (VolumeTool), a single transverse slice at the L3 vertebra was used to (semi automatically) segment the visceral fat area , subcutaneous fat area, total muscle area and muscle attenuance(figure 1). Muscle attenuation was defined as the density of the muscle, which decreases with increased lipid content. Subsequently the ratio between visceral and subcutaneous fat was calculated. Cox regression analyses was performed to determine the association between the variables of interest and survival at 90 and 365 days, adjusted for potential confounders (age, sex, primary tumor, Karnofsky performance scale, number of bone metastases, non-bone metastases and neurological symptoms). Results Patients had a median age of 67 years, and 63% were male. The most common primary tumors were lung (28%), prostate(27%) and breast(18%). Median follow-up was 197 days, overall survival rates at 90 and 365 days were 71% and 36% respectively. In univariable analysis, subcutaneous fat area, fat ratio and muscle attenuance were significantly associated with survival at 90 and 365 days. After adjustment, only muscle attenuance was significantly associated with 90 and 365 days survival, HR: 0.89 (95% CI 0.84-0.94) and HR: 0.93 (95% CI 0.89- 0.97)respectively. with overall survival. Material and Methods

1 University Hospital Madrid Sanchinarro, Radiation Oncology, Madrid, Spain Purpose or Objective To evaluate the effectiveness and toxicity of stereotactic ablative radiation therapy (SART) for non-spinal bone metastases. Material and Methods From May 2013 to August 2017, 48 non-spinal bone metastasis of 43 patients were treated with SART, 47 metastasis underwent 30 Gy in 3 fractions and 2 lesions received 35 Gy in 5 fractions, delivered every single day in a Linear Accelerator Novalis with inter and intra- fraction orthogonal X-ray imaging guidance (IGRT). Intensity-modulated radiotherapy (IMRT) was performed in 44 lesions (90%) and 3D-conformal radiotherapy in 5 treatments (10%). Patients were reviewed at the end of treatment and one, three and six months afterward. Pain control was documented with the Visual Analogue Scale (VAS) and the radiological response was determined with the MD Anderson Cancer Center Criteria (MDA criteria).

Conclusion This study showed that muscle attenuance was significantly associated with the overall survival of patient with spinal metastases. CT-scans, which are routinely available in the majority of patients with spinal metastases, contain useful information and can contribute to better selection of patients for surgical stabilization of spinal metastases. EP-1628 Stereotactic Ablative Radiotherapy for non- spinal bone metastasis. A single institution experience A. Acosta Rojas 1 , M. Nuñez 1 , A. Montero-Luis 1 , E. Sanchez-Saugar 1 , O. Hernando-Requejo 1 , R. Ciervide- Jurio 1 , M. Lopez-Gonzalez 1 , M. Garcia-Aranda 1 , J. Valero- Albarran 1 , M.C. Rubio-Rodriguez 1

Results With a median follow-up of 14.5 months (1-64 month) 27 patients (56.25%) are alive, 20 patients (41.6%) death for progression of the disease and 1 patient (2.33%) death related to comorbidity. Complete local pain control was reported in vast majority of patients (graphic 1). 38 lesions (79.17%), 26 lesions (54.17%) and 19 lesions (39.58%) were radiologically evaluated with MDA criteria at 3, 6 and 9 moths respectively (table 1). Local progression free survival was 92.1% at 12 months; 83.3% at 24 and 36 months.