ESTRO 2022 - Abstract Book

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Abstract book

ESTRO 2022

elderly patients. The aim of this study was to evaluate the effectiveness and safety of the hypofractionated radiotherapy (HRT) in patients with GB. Materials and Methods This is a retrospective study analyzing the data of 37 patients with GB treated between 2016 and 2020. The median age was 60 years [15-84] (HRT: 72 years; SRT: 66 years) and the performance score (WHO) was ³ 2 in 64% of cases. The median tumor size was 52 mm [3-9,6]. Adjuvant SRT was performed in 70.3% of cases and HRT (40 Gy in 15 fractions) in 29.7% of cases, depending on age and initial WHO score. Concomitant and adjuvant Temozolamide was administered in 51.4% of cases (only for patients treated by SRT). The primary end-point was the effectiveness of the HRT evaluation by analyzing the overall survival (OS) and disease-free survival (DFS) rates. Clinical assessment of radiation-induced toxicities was performed at the end of radiotherapy sessions using a questionnaire based on the RTOG clinical scales. Assessement of patients quality of life was based on the EORTC QLQ-BN20 questionnaire. Results Median OS was 12 months [5-23] and 6 months [3-13] respectively for SRT and HRT (p = 0.01). Median DFS was 8 months [1-18] and 2 months [1-6] respectively for SRT and HRT (p = 0.01). Multivariate analysis showed that OS predictive factors were the age (age >60 ans; p=0.003), the WHO score (WHO >=2; p=0.001), the type of adjuvant treatment (RT alone; p<10 - 3 ) and the fractionation regimen (HRT; p=0.001). For DFS, the predictive factors were: the WHO score (WHO >=2; p=0.004), the type of adjuvant treatment (RT alone; p=0.007) and the fractionation regimen (HRT; p=0.006). For older patients (>65 years old), those with larger tumor (>65 mm) or higher WHO score (>=2) there were no survival rates differences between HRT and SRT neither for OS (p=0.2,p=0.09 and p=0.1 respectively) nor for DFS (p=0.6,p=0.1 and p=0.4 respectively). For elderly patients, quality of life and acute radiation-induced toxicities (nausea,vomiting, alopecia and cerebral edema), were similar between SRT and HRT. Conclusion The results of this study show the non-inferiority of HRT compared to SRT in terms of survival and disease control outcomes with less radiation-induced toxicities, especially for older patients and those with poor prognosis factors, maintaining a good quality of life. It could be a reasonable therapeutic approach in elderly patients with less favourably prognosis factors. 1 Odense University Hospital , Department of Oncology , Odense , Denmark; 2 University of Southern Denmark , Department of Clinical Research, Odense , Denmark; 3 Odense University Hospital , Department of Oncology, Odense, Denmark; 4 University Hospital of Southern Denmark, Lillebaelt Hospital, Department of Oncology, Vejle , Denmark; 5 Kalmar County Hospital, Department of Oncology, Kalmar, Sweden; 6 Odense University Hospital, Laboratory of Radiation Physics, Department of Oncology, Odense , Denmark; 7 Odense University Hospital, Department of Oncology, Odense , Denmark Purpose or Objective Improved overall survival (OS) due to advances in cancer treatment and improvements in neuroimaging results in an increasing number of patients presenting with brain metastases. Stereotactic radiosurgery (SRS) is increasingly used instead of whole-brain radiotherapy (WBRT) for patients with limited brain metastases, as WBRT has known side effects, which are of increasing concern due to improvement in prognosis. The benefits of SRS compared to WBRT include reduced toxicity, as it is possible to reduce the radiation dose to the whole brain and an expected increase in local control. However, despite treatment advances, the prognosis for the majority of patients with brain metastases remains poor. This study aimed to evaluate survival after the first treatment with SRS and identify groups of patients with a better prognosis. Materials and Methods Patients from a single institution with up to four brain metastases, diameter <3 cm, treated from April 2011 to February 2018 were included, regardless of the primary cancer diagnosis. Single metastases between 3 and 4 cm were allowed. Patients were prospectively registered, and clinical data were gathered retrospectively (tumor histology, performance status (PS), age, and number of metastases). As follow-up procedure, MRI was performed one month after treatment and every 3rd month hereafter. In case of progression or recurrence, the possibility of SRS, WBRT, surgery, systemic treatment, or best supportive care was evaluated. No patients were lost to follow up. The dose to the edge of the gross tumor volume (GTV) was 20 Gy/ 1 F or, in case of larger metastases or proximity to organs at risk, 27 Gy/ 3F. All patients were planned with CT- and MR scans. Radiologists and oncologists in collaboration defined GTV. The treatment was performed with three arcs on a linac, one coplanar and two non-coplanar. Orfit® 5-points immobilization system was used. PTV margin was 2-3 mm. Results In total, 285 patients were treated with SRS. Baseline characteristics in table 1. The median survival was eight months. OS after 1 and 2 years was 29% and 13% respectively. Median survival for breast cancer patients was 19.4 months, 9.8 months for malignant melanoma, and 7.6 months for lung cancer patients. Patients with a PS 0-1 and breast cancer diagnosis had significantly better survival. Patients with PS ≥ 2 had a median survival of only four months (table 2). In a cox regression analysis PS, female sex and breast cancer diagnosis had a statistically significant positive impact on survival, whereas number of brain metastases (1 vs ≥ 2) and age ≤ 70 did not. PO-1140 Survival after stereotactic radiosurgery for brain metastases – A single-institution experience A. Olloni 1,2 , O. Hansen 3,2 , C. Kristiansen 4 , L. Edvardsson 5 , M. Nielsen 6 , S.S. Jeppesen 7,2 , T. Schytte 7,2

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