ESTRO 38 Abstract book

S462 ESTRO 38

status and the presence of metastatic sites other than the thoracic nodes were correlated both with OS and PFS. Local response was a predictor of OS. Conclusion SBRT for thoracic nodes was safe and feasible. Higher RT doses were correlated to better LC and should be taken in consideration at least in patients with isolated nodal metastases and colorectal histology. PO-0877 Utilization of short course palliative radiation therapy in breast cancer bone metastasis P. Gabani 1 , B. Fischer-Valuck 2 , W. Kennedy 1 , L. Ochoa 1 , M. Thomas 1 , M. Daly 1 , I. Zoberi 1 , C. Abraham 1 1 Washington University in Saint Louis, Radiation Oncology, Saint Louis, USA ; 2 Emory School of Medicine, Radiation Oncology, Atlanta, USA Purpose or Objective Breast cancer is one of the most common malignancies associated with bone metastasis. Recent evidence suggests equivalent palliative efficacy between short course RT (i.e. ≤ 5 fractions) and long course RT (≥ 10 fractions) for the palliation of bone metastasis. Despite this, the uptake of short course RT remains low. This is an observational study of a large national cohort evaluating the patterns of care associated with various palliative RT fractionation schemes for the treatment of breast cancer bone metastases. Material and Methods Patients with metastatic breast cancer bone metastasis from 2010 – 2015 were obtained from a national cancer database. Patients who were treated with palliative RT to bone lesions with 8 Gy in 1 fx or 20 Gy in 5 fx were categorized as short course RT (SC-RT). Patients who were treated with palliative RT to bone lesions with 30 Gy in 10 fx or 37.5 Gy in 15 fx were categorized as long course RT (LC-RT). Patients receiving other RT fractionation schemes were excluded. Patients receiving RT to the spine for cord compression were excluded. Multivariable logistic regression analysis was used to evaluate factors associated with the receipt of SC-RT. Exact match using propensity score was used to balance the baseline patient characteristics between SC-RT and LC-RT. Overall survival (OS) was estimated with Kaplan-Meier method. Multivariable Cox proportional hazards model was used to evaluate factors associated with OS. Significance was defined at a value of p < 0.05. Results A total of 4816 patients were included in the analysis: 737 (15.3%) received SC-RT and 4079 (84.7%) received LC-RT. The median follow up was 24.3 months (range: 0.8 – 84.7). The utilization rate of SC-RT increased significantly from 10.7% in 2010 to 20.7% in 2015 (p < 0.01). On multivariable analysis, factors that were associated with a higher likelihood for the receipt of SC-RT were age ≥ 60 (ref = age <60, OR 1.27 (1.06 – 1.52), p = 0.01), treatment to extremities (ref = spine, OR 2.15 (1.69 – 2.74), p< 0.01), treatment to ribs (ref = spine, OR 3.15 (1.76 – 5.63), p< 0.01), treatment at an academic/research program (ref = community cancer program, OR 1.78 (1.47 – 2.17), p < 0.01), and triple negative breast cancer (ref = hormone positive, OR 2.29 (1.72 – 3.04), p < 0.01). On multivariable analysis, SC-RT was associated with a worse OS compared to LC-RT (HR 1.38 (1.20 – 1.59), p< 0.01). The 3-yr OS was 31.9% in SC-RT vs 47.9% in LC-RT group (Fig 1A, p< 0.01). However, after exact match using propensity score, there was no difference in the 3-yr OS between the two groups (53.1% vs. 45.0%, Fig 1B, p = 0.21).

endocrinological follow-up in less than 2 years. Therefore, 64 patients were evaluated: 32 medulloblastomas (50.0%), 17 gliomas (26.5%), 7 germinomas (10.9%), 3 ependymomas (4.6%), and 5 other histological types (7.8%) (2 Ewing sarcomas, 1 PNET, 1 pinealoblastoma, 1 ATRT). 61 pts also underwent to chemotherapy and 42 to surgery. The mean pituitary dose in patients with GHD was 36.5 ± 9.78 Gy (p 0.01), TSHD 38.0 ± 6.0 Gy, ACTHD 34.6 ± 10.5 Gy.Patients treated with 3DCRT had a higher risk of developing GHD, ACTHD, and TSHD when compared to those treated with IMRT techniques (p <0,05). The "safe dose" to under which no patient has shown GH deficiency is <10 Gy while for TSH and ACTH deficit is <20 Gy. Conclusion Our data underline the role of pituitary dose on endocrine deficits; IMRT should be the preferred technique in the treatment of paediatric CNS . PO-0876 Stereotactic Body Radiation Therapy for thoracic nodes metastases, a multi-institutional experience D. Franceschini 1 , F. Bianciardi 2 , R. Mazzola 3 , F. De Rose 1 , P. Gentile 2 , F. Alongi 3,4 , M. Scorsetti 1,5 1 Humanitas Research Hospital, RADIOTHERAPY AND RADIOSURGERY, Rozzano Milan, Italy ; 2 San Pietro Fatebenefratelli Hospital, Radiation Therapy Department, Rome, Italy ; 3 IRCCS Sacro Cuore Don Calabria Hospital, Radiation Oncology Department, Negrar-Verona, Italy ; 4 University of Brescia, Radiation Oncology Department, Brescia, Italy ; 5 Humanitas University, Department of Biomedical Sciences, Rozzano- Milano, Italy Purpose or Objective To evaluate safety and efficacy of Stereotactic Body Radiation Therapy (SBRT) in patients with thoracic nodes oligometastases Material and Methods The present study is a multicenter analysis. Oligometastatic patients, affected by a maximum of 5 active lesions in 3 or less different organs, treated with SBRT to thoracic nodes metastases between 2012 and 2017 were included in the analysis. Primary end point was local control (LC), secondary end points were overall survival (OS), progression free survival (PFS), acute and late toxicity. Univariate and multivariate analysis were performed to identify possible prognostic factors for the survival endpoints. Results 76 patients were included in the analysis. Different RT dose and fractionation schedules were prescribed according to site, number, size of the lymph node(s) and to respect dose constraints for relevant organs at risk. Median BED delivered was 75 Gy (interquartile range: 59- 86 Gy). Treatment was optimal; one G1 acute toxicity and 7 G1 late toxicities of any grade were recorded. Median follow up time was 23.16 months. Sixteen patients (21.05%) had a local progression, while 52 patients progressed in distant sites (68.42 %). Median LC was not reached, LC at 6, 12 and 24 months was 96.05% (CI 88.26-98.71%), 86.68% (CI 75.86-92.87) and 68.21% (CI 51.89-80.00%), respectively. Median OS was 28.3 months (interquartile range 16.1-47.2). OS at 6, 12, 24 and 36 months was 98.68% (CI 91.03-99.81%), 86.34% (CI76.07-92.42%), 55.98% (CI42.61-67.40%) and 41.61% (CI 27.85-54.80%), respectively. Median PFS was 9.2 months (interquartile range 4.1-17.93). PFS at 6, 12 and 24 months was 63,16% (CI 51.29-72.89%), 34.99% (CI 24.22-45.94%) and 16.84% (CI 8.91-26.92%), respectively. At multivariate analysis, RT dose, colorectal histology, systemic therapies were correlated with LC. Performance Poster: Clinical track: Palliation