ESTRO 38 Abstract book

S671 ESTRO 38

and should be considered if tissue diagnosis is not available. EP-1212 Clinical outcome in brain metastases from breast cancer treated with stereotactic radiotherapy G. Riva 1 , A. Ferrari 1 , S. Durante 1 , D. Ciardo 1 , G. Piperno 1 , M.C. Leonardi 1 , S. Vigorito 2 , E. Rondi 2 , R. Orecchia 3 , B.A. Jereczek-Fossa 1 1 Istituto Europeo di Oncologia - IEO, Radiotherapy, MIlan, Italy ; 2 Istituto Europeo di Oncologia - IEO, Medical Physics, MIlan, Italy ; 3 Istituto Europeo di Oncologia - IEO, Scientific Director, MIlan, Italy Purpose or Objective The objective of this study was to report our institutional experience with CyberKnife in the stereotactic radiation treatment (SRT) of patients with brain metastases. Material and Methods One-hundred and two consecutive patients with brain metastases from breast cancer (199 lesions) were treated with brain SRT with CyberKnife from 02/2012 to 11/2017 as first brain radiation treatment and reviewed retrospectively for patient, tumor, and imaging characteristics. Parameters included demographics, histology and primary tumor characteristics, presence and control of extracranial disease, number of lesions and tumor volume. The imaging characteristics assessed were complete response (CR), partial response (PR), stable disease (SD), local (LF) and distant brain failure (DBF). Overall survival (OS) and local control (LC) at 2 years were evaluated Results After a median follow-up of 11.6 months (range 2.6–65.6), at least one radiological evaluation was available for 152 brain metastases (76 patients, all women). Most of the lesions (41%) were treated with a single session of SRT with a total dose of 21 Gy, other fractionations (24 Gy in 2 or 3 sessions) were preferred in case of two or more concomitant metastases or in case of greater volume of the target. CR, PR and SD as best response were reported in 67 (44%), 56 (37%) and 26 (17%) of 152 lesions respectively, while 3 (2%) lesions had a progression disease at first control. Fifteen out of 149 (10%) lesions showed LF after a median of 12.5 months (range 1.2–63.4). Forty-seven (61%) women out of 76 developed DBF after a median of 7.0 months (range 1.0–39.6). Radionecrosis was radiologically (11c-methionine Positron Emission Tomography and/or Nuclear Magnetic Resonance with gadolinium) diagnosed for 14 lesions (13 patients, 17%) in a median time of 7.3 months (range 2– 20.4). Seven (9%) women referred neurological symptoms (such as seizures), a neurosurgical treatment was needed for 3 of them in order to control symptoms. At the time of assessment, 36 (47%) patients are still alive, 32 (42%) died for tumor progression and 8 (11%) were lost to follow-up. OS after 2-years is 52%, LC after 2-years is 63%.

Conclusion Our results showed the efficacy in the treatment of brain metastases from breast cancer with CyberKnife SRT. Correlation between clinical (volume of brain disease) and histological parameters with favorable outcome is under investigation. EP-1213 Prediction of new brain metastases after radiosurgery: validation of two nomograms in our serie. C. De la Pinta Alonso 1 , R. Hernánz 1 , E. Fernández- Lizarbe 1 , M. Martín 1 , C. Vallejo 1 , M. Martín Martín 1 , A.B. Capúz 2 , S. Barrio 3 , M. Torres 3 , S. Sancho 1 1 Ramón y Cajal Hospital, Radiation Oncology, Madrid, Spain ; 2 Ramón y Cajal Hospital, Medical Physics, Madrid, Spain ; 3 Ramón y Cajal Hospital, Radiotherapist, Madrid, Spain Purpose or Objective Prediction of patients at highest risk for brain recurrence after radiosurgery remains a clinical concern. The aim of our study was to evaluate two published nomograms (Ayala et al and Rodrigues et al) to predict the risk of brain recurrence in a Spanish-population treated with radiosurgery in our institution. Material and Methods We retrospectively identified 85 patients diagnosed of brain metastases who had undergone radiosurgery from 2006 through 2018 at the Ramón y Cajal University Hospital (Madrid). Clinical factors and performance status of the nomograms for prediction of brain recurrence were assessed. Results Median follow-up time was 9 months. Among the 85 patients, 13 (15.3%) developed brain recurrence. We evaluated our data set with the nomograms models. Because of missing data, 12 of the 85 patients were excluded. We analyzed 3, 6, 9-months probabilities of recurrence in Ayala nomogram and 1-year with the Rodrigues nomogram. Only patients with brain recurrence were included in our validation. Calibration for 3, 6, 9- months to and 1-year probability of free brain recurrence for the nomogram showed good model calibration with intermediate correlation of nomogram-predicted probability of brain recurrence and observed probability of brain recurrence as estimated by the Kaplan-Meier method. The best correlation was in terciles in Ayala nomogram and deciles in Rodrigues nomogram. We have stratified patients in three groups in Ayala nomogram: low risk of recurrence (11-79points), intermediate risk (80- 140points) and high risk (140-260points). We have stratified patients in two groups in Rodrigues nomogram: