ESTRO 2020 Abstract book

S514 ESTRO 2020

campimetric control, stabilization in 50%, and worsening in 18.8%. 3.6% required rescue treatment. No acute toxicity in 66.7%, being headache the most frequent. In 89.7% no late toxicity. At the end of the study, only one patient died due to the tumor. Conclusion Fractionated Stereotactic Radiotherapy (FSR) is a well- tolerated therapeutic approach with excellent local control, useful in the treatment of intracranial tumors such as craniopharyngiomas. It is useful in the treatment of bulky intracranial tumors and located near critical risk organs. PO-0873 Lung Cancer Brain Metastasis: Higher Biologically Effective Dose Radiotherapy may improve survival. F.A. Lima Aires 1 , E.D. Rodrigues Pinto 1 , M.M.A. Reis Lima Marques 1 , M.G. Pinto 1 1 Centro Hospitalar Universitário de São João, Radioncology, Porto, Portugal ) impact evaluation on specific survival in patients with Brain Metastatic Lung Cancer treated with palliative Radiation Therapy (RT). Material and Methods This retrospective study was based on RT Department electronic health records collected on May 2019. This study was approved by the institutional ethical review board. All patients with Brain Metastastatic Lung Cancer treated with RT between January 2013 and December 2017 were included (n=114). Patients who underwent radiosurgery and brain metastasectomy prior to RT were excluded. Patient, tumour, and treatment characteristics were collected. Biologically relevant covariates, including dose per fraction, number of fractions were used to quantify BED 10 and radiation treatment schedule. The linear-quadratic equation was used to calculate BED 10 and to generate a dichotomous dose variable of ≤30 Gy versus >30 Gy BED 10. Survivals were estimated based on the Kaplan-Meier method and their comparison of survival curves, performed using the log-rank test. An analysis by age group (<70 vs ≥70 years old) was performed. Cox proportional hazards regression modeling was used to assess associations between the BED and the outcome of death caused by lung cancer, adjusted for significant clinical covariates (p<0.05). The IBM SPSS v.25 software was used for statistical analysis. Results Patient, tumour and treatment characteristics are listed on Table 1. The median age was 64 years. The predominant stage was IVA (n =103). Performance status (ECOG-PS) 0-1 were predominant. The number of treated brain metastases were 1 (n=38), 2 (n=27), 3 (n= 19) and ≥4 (n=30). The median BED 10 was 39 Gy and 90 patients (78.9%) had died by cancer disease. The median follow-up time was 8,2 months (0,56-62,9 months). Cox analysis significant covariates identified were stage (IVA vs IVB), ECOG-PS (0-1 vs 2-3) and immunotherapy treatment. Higher stage and ECOG-PS were associated with increased likelihood of lung-cancer death and the opposite was seen for immunotherapy. The 83 patients receiving >30Gy BED 10 had a median survival of 5.4 months (95% CI 3.9-6.9), whereas the 31 patients receiving ≤30 Gy BED 10 had a median survival of 3.6 months (95% CI 2.6-4.5), p = 0.501. Stratified age group analysis showed a trend (p>0.05) to greater benefit for patients under 70 years old receiving whole-brain radiotherapy >30Gy BED 10 . Purpose or Objective Biologically effective dose (BED 10

Conclusion In our brain metastatic lung cancer cohort, we found that biologically effective dose radiation therapy>30Gy BED 10 may improve survival and with a greater benefit for patients aged under 70 years old.