ESTRO 2024 - Abstract Book

S866

Clinical - CNS

ESTRO 2024

Purpose/Objective:

Brain metastases occur in 9-40% of all cancer patients during the course of their disease. Therapeutic options include Stereotactic Radiotherapy (SRT). In order to personalized the best treatment regimen, an easy-to-perform Prognostic Score could be useful to guide treatment decisions. The aim of the study is to evaluate the clinical outcomes of the SRT and the Comprehensive Prognostic Index (CPI).

Material/Methods:

We retrospectively analyzed 83 patients treated with SRT for brain metastases between 2015 and 2022. All patients had a KPS score of ≥ 70. The histological type of the primary lesion, extent of extracranial metastatic disease and the characteristics of brain metastases were verified by reviewing medical records and imaging. Overall survival (OS) and local control (LC) were determined. The Comprehensive Prognostic Index was calculated according to Stankiewicz et al. 1 and it included Karnofsky Performance Status, number of brain metastases, volume of the largest lesion, and presence of extracerebral metastases. Patients were divided into four groups based on the obtained CPI Score: group 1 (0-1 points), group 2 (2-3 points), group 3 (4- 5 points) and group 4 (≥6 points). The OS was compared to Comprehensive Prognostic Index in order to verify the prognostic value of the index: higher scores related to worse OS. The responses were divided in complete and in partial ones and they were analyzed with LC. Treatment outcomes were evaluated using Kaplan – Meier analysis. A P-value less than 0.05 was considered statistically significant. The median age was 63 years old. Female/Male ratio was 60%/40%. Non – small cell lung cancer (47%) and breast cancer (29%) represented the most common primary tumors. 26% of patients had uncontrolled systemic metastatic disease. The median number of treated brain metastases was 1,5 lesions per patient (range: 1-4 metastases). The most used RT schedule was 27 Gy (9 Gy/day) followed by 24 Gy (8 Gy/day). The median follow-up was 12 months (range: 2-56 months). 60% of patients achieved a lesion response of which 50%, a complete response. The 1-year and 2-year OS rates were 51%, and 39%, respectively. The median time for lesion max response was 4 months. The 1-year and 2-year LC rates were 58%, and 39%, respectively. Figure 1 shows that Complete Response patients had a better and longer LC compared to Partial Response patients (6 months LC: 97% vs 25%, p<0,001). In terms of prognostic value of Comprehensive Prognostic Index, it was showed that Group 4 had a 5-times higher risk of lower OS compared to Group 1 (p<0,001); whereas Group 2 and 3 had 3-times higher risk (p=0,05 and p=0,02 respectively. Results: