ESTRO 38 Abstract book

S881 ESTRO 38

evaluated with visual analogic scale (VAS) (0-3: light; 4-6: moderate; 7-10: intense). Results Mean age at the bone metastases diagnoses was 56 years (range: 32-85 years). The most common primary tumour was breast cancer (58%), followed by lung cancer (16%), renal cell carcinoma (9%) and prostate cancer (6%). For metachronous metastases the mean interval between primary tumour diagnoses and bone metastasis diagnoses was 4,5 years (range: 0-18 years). Synchronous primaries and metastases appeared in 30% of patients. Most metastases (80%) were located in the spine, especially thoracic and lumbar vertebras. Others sites were pelvis, breastbone, ribs and femur. Radiologically, 52% were sclerotic, 30% were lytic and 18% were mixed metastases. The maximum number of treated lesions per patient was 4. The mean total dose for macroscopic tumour was 29 Gy (range: 18-35 Gy) and for adjacent bone was 22 Gy (range: 20-30 Gy). Local control rate, including complete response, partial response and stable disease was 75%. Two year overall survival was 73,7%. The mean following time was 386 days. Four patients died during the follow- up. Before treatment, 16% suffered moderate pain and 30% intense pain. After treatment, 8 patients achieved complete control (VAS 0); 7 presented partial control (lower VAS); 12 kept stable; 4 patients did not achieve symptomatic control. The mean reduction of VAS after SBRT was 2 points. Forty-two percent achieved reduction of VAS ≥3 (range 3-8). No spinal cord toxicity was observed. Conclusion SBRT is a treatment option for BM because local control and pain control without toxicity are achievable in most of cases. EP-1635 Stereotactic ablative radiation therapy for non-spine bone metastases K.S. Kim 1 , C. Choi 1 1 Dongnam Institute of Radiological and Medical Sciences, Radiation Oncology, Busan, Korea Republic of Purpose or Objective To report the treatment outcome of stereotactic ablative radiation therapy (SABR) for non-spine bone metastases in a single institution Material and Methods From Jul. 2011 to Jan. 2017, thirty-three patents with non-spine bone metastatic disease were treated with SABR. Treatment intent were categorized as follows (1) Single metastasis or oligometastases, for which the goal was to irradiate all sites of disease; (2) Oligoprogression, for which the goal was to irradiate only those tumors that were progressing while an systemic therapy was controlling all other sites of disease; (3) Dominant areas of progression, for which the goal was to irradiate dominant tumors usually for palliation. A total of 38 lesions were treated and responses were evaluated according to University of Texas MD Anderson (MDA) cancer center criteria. Results The most common primary cancer was non-small cell lung cancer (n=12) following breast cancer (n=8), hepatocellular carcinoma (n=3) and renal cell carcinoma (n=3). Twenty-five lesions (66%) were located in the pelvis following femur (n=5) and ribs (n=5). Majority of the lesions were lytic bone metastases (n=25, 66%). Prescribed radiation doses and fractions were 18 Gy/1 fraction (Fx) to 3 lesions, 24-60 Gy/3 Fx to 16 lesions, 28-48Gy/4 Fx to 15 lesions and 40-50 Gy/5 Fx to 4 lesions. Median follow up periods was 10.4 months (2.5-47.4). One-year local control rate was 94.2%. Median overall survival was 25.1 months (95% CI 14.7-35.5 month) for single metastasis or oligometastasis (n=24), 25.7 months (95% CI 0-54.2) for oligoprogression (n=3) and 5.8 months (95% CI 2.0-9.6) for

Conclusion As expected, the highest mortality incidence at 30 days was found in patients with worse PS, wich in the majority of cases were treated with single doses, and in those with presence of visceral metastases. The largest fractionation schemes included in this group were prescribed in patients with WBRT intention. Knowing these data is useful for treatment decision making as well as selection of dose-fractionation prescription. This could help to avoid futility and non- beneficial treatment during the end of life. EP-1634 Stereotactic Body Radiotherapy (SBRT) for bone metastases: Preliminary experience E. González Del Portillo 1 , O. Alonso-Rodríguez 1 , A. Nieto- Palacios 1 , C. Martín-Rincón 1 , L.A. Pérez-Romasanta 1 1 Complejo Asistencial Universitario de Salamanca, Radiation Oncology, Salamanca, Spain Purpose or Objective Bone metastases (BM) are common in patients with advanced solid tumours causing pain, disability, increased fracture risk, and having a negative impact on patient’s quality of life. Stereotactic body radiotherapy (SBRT), also referred to as stereotactic ablative radiotherapy (SABR), is an emerging option of treatment for these metastases. It is characterized by either a single or limited number of dose fractions, and a high biological effective dose, often above 100 Gy. Its effects are higher cell death, lower DNA repair mechanisms, damage to tumour vasculature, and activation of immune system. Our goal is to evaluate local control, survival, pain control and complications. Material and Methods This is a prospective study from 2014 to 2018. We included 31 oligometastatic patients and 44 BM treated with SBRT. Patients received a total dose of 20-35 Gy, typically in 5 consecutive fractions. Most treatments included an extended volume with simultaneous integrated boost on the macroscopic tumor, following standardized consensus for volume definition. Daily 3D imaging for verification purposes was done before treatment. The endpoints were radiological response and local control (control included complete response, partial response and stable disease), survival rate by Kaplan-Meier method, and pain control