ESTRO 2023 - Abstract Book
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ESTRO 2023
OS rate of 80%. Radiological radionecrosis was detected in 3 pts (10%), who developed G1 neurological symptoms managed with low-dose dexamethasone. Two pts discontinued SILLBRAIN® assumption due to G1 nausea. No other adverse events were reported. Conclusion At about half of our enrollment target, the results show a favorable trend towards 6-month DBF rate reduction. Toxicity proved manageable, consistent with the literature and limited to gastrointestinal effects. A larger sample and longer follow up is needed to confirm our hypothesis.
PO-1110 Radionecrosis in brain metastases, intact or cavities, treated with stereotactic radiotherapy
S. Fernandez Alonso 1 , S. Guardado González 1 , G. Pozo Rodríguez 2 , C. Arias Guillén 1 , C. F. Pedrero 1 , R. D´Ambrosi 1 , J.F. Pérez-Regadera Gomez 1 1 Hospital Universitario 12 de Octubre, Radiation Oncology, Madrid, Spain; 2 Hospital Universitario 12 de Octubre, Medical Physicist, Madrid, Spain Purpose or Objective To determine the incidence of radionecrosis (RN) and the factors associated with its appearance in patients treated with single-session radiosurgery (SF-SRS) or fractionated stereotactic radiotherapy (MF-SRS). Materials and Methods 183 patients (57% women and 43% men) diagnosed with 1 to 5 brain metastases (232 lesions) treated between 2013 and 2020 were included and retrospectively analyzed. An MRI was performed 3 months after RT and then every six months. The association between variables was established with the Fisher or Chi-square test and survival with the Log-Rank test.
Results Mean age was 59 years and mean lesion was 18mm (9-25mm). Primary tumor histology: NSCLC 51%, breast 25%, melanoma 8%, kidney 5%, colorectal 4%, other 7%. RPA classification: I 48% and II 52%. 49% had received previous local treatment; 67% WBRT, 23% surgery and 10% WBRT+surgery. 62% received SF-SRS. Dose administered: 15Gy 88%, 18Gy 10% and 2% other dose. 38% received MF-SRS. Dose administered: 35Gy (7x5Gy) 62%, 30Gy (6x5Gy) 25% and 13% other dose.
There were no significant differences between SF-SRS and MF-SRS in terms of age, lesion , sex, histology or RPA. Regarding previous local treatment, surgery was more frequent in MF-SRS (13% vs 3%) and WBRT in SF-SRS (27% vs 7%) (p=0.01). RN was observed in 19% of patients, with a median time of appearance of 6 months (3.5-16) post-treatment. 85% of RN occurred in the SF-SRS group and 15% in the MF-SRS group (p=0.01). The mean PTV volume of the lesions that developed RN was 4cc, with a compliance index of 1.7, isocenter dose mean 17.6Gy and marginal dose mean 14.6Gy. 44% of RN occurred in lesions between 10-20mm, 32% in those greater than 20mm and 24% in those less than 10mm. Using a ROC curve and the Youden`s index, the area under the lesion curve was 0.507 (0.402-0.612, p=0.05). The cut-off point was 15mm, with a sensitivity and specificity of developing RN of 68% and 46% respectively.
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