ESTRO 2020 Abstract book

S527 ESTRO 2020

PO-0901 Stereotactic radiotherapy in brain metastases. Survival and radiological behavior analysis. S. Fernandez Alonso 1 , S.G. Guardado Gonzáles 1 , G. Pozo Rodríguez 2 , D. Lora Pablos 3 , J.F. Pérez-Regadera Gómez 1 1 Hospital Universitario 12 de octubre, Radiation Oncology, Madrid, Spain ; 2 Hospital Universitario 12 de octubre, Radiophysics, Madrid, Spain ; 3 Hospital Universitario 12 de octubre, Statistics, Madrid, Spain Purpose or Objective To compare the characteristics, survival and radiological behavior among patients with 1-3 brain metastases treated by single-fraction radiosurgery (SF-SRS) or multi-fraction radiosurgery (MF-SRS) in our center. Material and Methods 163 patients were treated between January/2011 and June/2018 and were retrospectively studied. Results 40% patients were men and 60% women. Mean age was 56 years. There were no differences in age, sex, Karnofsky performance status, size of lesion, previous local or systemic treatment. Histological diagnosis was lung adenocarcinoma EGFR naive (23%), other lung carcinoma (19%), triple negative breast (10%), melanoma (9%) and other histologies (39%). At the date of onset of brain metastases, 66% patients had the primary tumor controlled. According to RPA classification 49% was I, 50% II and 1% III. 68% cases presented a single lesion, 19% 2 lesions, and 13% 3 or more lesions; 65% were supratentorial, 14% infratentorial and 21% had involvement of both locations. A single lesion was treated in 83% cases, 2 in 12%, 3 in 4% and in 4 in 1%. 51% patients had received previous cranial treatment; 65% whole brain radiotherapy (WBRT), 25% surgery and 10% surgery + WBRT. 75% had received systemic treatment; 49% QT, 22% QT + immunotherapy, 15% exclusive immunotherapy, 9% QT + hormone therapy and 5% other treatments. 63% patients received MF-SRS (58% 7x500 cGy, 29% 6x500 cGy and 13% another fractionation). 42% patients received SF-SRS (95% 15 Gy, 3% 18 Gy and 2% another dose). 95% finished radiotherapy treatment. 62% received systemic treatment in the first month after One-year survival of group treated with MF-SRS was 93% and of SF-SRS group 90%. Five-year survival was 53% and 59% respectively ( p =0.88). 42% progressed locally and 22% failure remote; of them, 49% had received MF-SRS and 51% SF-SRS ( p =0.58). Median time to local failure was one year and until remote failure three years. One and five-years survival of patients with progression were 81% and 49% in MF-SRS group and 79% and 51% in SF- SRS group ( p =0.95). Regarding radiological behavior at 3 months, 5% presented complete response (CR), 28% partial response (PR), 47% stable disease (EE) and 20% progression (PD). At 6 months, 11% had CR, 47% PR, 25% EE and 17% PD. At one year 17% had CR, 38% PR, 20% EE and 25% PD. At the end of the study 47% patients had died, 25% remain alive without disease, 12% are alive with extracranial disease, 7% with exclusive intracranial disease, 3% with intracranial and extracranial disease and 6% are unknown. Cause of death was systemic in 46%, cerebral in 37% and 17% foreign to tumor cause. Conclusion SF-SRS and MF-SRS are an effective treatment in brain metastases. There are no differences between SF-SRS y MF-SRS in survival and local control. RT; 40% QT and 60% other treatments. Median overall survival was 3.28 years.

PO-0900 Radionecrosis in patients with brain metastases treated with stereotactic radiotherapy. S. Fernandez Alonso 1 , S.G. Guardado Gonzáles 1 , G. Pozo Rodríguez 2 , D. Lora Pablos 3 , J.F. Pérez-Regadera Gómez 1 1 Hospital Universitario 12 de octubre, Radiation Oncology, Madrid, Spain ; 2 Hospital Universitario 12 de octubre, Radiophysics, Madrid, Spain ; 3 Hospital Universitario 12 de octubre, Statistics, Madrid, Spain Purpose or Objective To determine the incidence of brain radionecrosis (RN) and its relation with the type of treatment received. Material and Methods 163 patients with 1-3 brain metastases were treated in our center with single-fraction radiosurgery (SF-SRS) or multi- fraction radiosurgery (MF-SRS) between 01/01/2011- 01/06/2018 and were included in this retrospective study. Patients were clinically evaluated 1 and 3 months after treatment and then every 6 months. Brain MRI was performed at 3 months after treatment and then every 6 months. RN diagnosis was radiological. Results 40% patients were men and 60% women. Mean age was 56 years. Primary tumors were lung adenocarcinoma EGFR naive (23%), other lung carcinoma (19%), triple negative breast (10%), melanoma (9%) and other histologies (39%). According RPA classification 49% was I, 50% II and 1% III. Median overall survival was 3.28 years. 51% patients had received previous cranial treatment; 65% whole brain radiotherapy (WBRT), 25% surgery and 10% surgery + WBRT. 63% patients received MF-SRS (58% 7x500 cGy, 29% 6x500 cGy and 13% another fractionation). 42% patients received SF-SRS (95% 15 Gy, 3% 18 Gy and 2% another dose). Dose was prescribed to 85% isodose line to get at least 95% target coverage of prescribed dose. Immobilization was performed in 47% with a bloody Radionics guide, in 45% with a frameless system (Brainlab mask) and in 8% with a reclining Radionics guide. RN incidence was 16%. It appeared in 22.4% of SF-SRS group and in 6.9% of MF-SRS with a median appearance of 7 months from stereotactic radiotherapy (p=0.012). Of the total cases of RN, 50% had received previous cranial irradiation (70% 10x300 cGy and 30% 14x250 cGy), however there was no relation between RN and previous cranial irradiation or surgery (p=0.371). Of the RN that appeared among patients treated with MF- SRS, 100% were symptomatic while patients treated with SF-SRS 40% were symptomatic and 60% asymptomatic. Treatment of RN was Bevacizumab in 63%, Bevacizumab + corticosteroids in 7%, corticosteroids in 10% and surgery in 3%. 17% patients did not receive treatment. As for the patients who received bevacizumab, 42% received 6 cycles, 5% 5 cycles and 21% 4 cycles. 16% received less than 4 and another 16% more than 6 cycles. At 4 months 26% of patients treated with Bevacizumab had lesion reduction and 42% stable disease. 32% remaining lost follow-up. There was no relation between the number of bevacizumab cycles and radiological response at 4 months (p = 0.26). Conclusion RN is the most significant complication in patients treated with brain stereotactic radiotherapy. The incidence of RN is higher in patients treated with SF- SRS, however it is more frequently symptomatic in patients treated with MF-SRS. This can be explained by the greater field irradiated in these patients since the size of the lesions is usually larger. Bevacizumab is a treatment option for these patients.