151 Impact of Post-Operative Radiotherapy (PORT) on Local Progression and Overall Survival in Patients with Cerebral Metastases: A Single-Centre Cohort Study

Abstract Introduction The optimum adjuvant treatment following operative removal of brain metastasis remains controversial. At our centre, post-operative radiotherapy (PORT) is offered to patients with radiological residual disease or intraoperative concerns such as piecemeal resection guided by post-operative multidisciplinary team (MDT) review. We evaluated the impact of PORT on overall survival (OS) and progression-free survival at the treated site. Method Data were collected retrospectively from adult patients undergoing surgical resection of brain metastases between 2020 and 2025. Demographic, clinical, and treatment-related data were collected. OS was defined as time from surgery to death or last follow-up. Local progression was determined radiographically. Survival outcomes were estimated using the Kaplan–Meier method and compared using the log-rank test. Results 74 patients underwent resection during the study period. 20 patients (27%) had synchronous metastatic disease at presentation; melanoma and lung cancer were the most common primaries. PORT was recommended in 32 patients (43.2%), with 22 (29.7% overall) receiving treatment. Median OS was 447.5 days in the PORT group versus 218.0 days in the non-PORT group (p = 0.15). Median time to progression was 440.5 days with PORT compared to 134.0 days without (p = 0.083). Reasons for non-delivery despite recommendation included clinical deterioration, poor performance status, interval cavity reduction, or patient preference. Conclusions PORT following resection of brain metastases demonstrated a non-statistically significant trend toward improved OS and delayed progression, despite PORT only being given where a metastasis was considered ‘high risk’ for recurrence. Findings are limited by small sample size and the single centre nature of the study, confounding due to PORT recommendations not being followed, and variable follow-up. Larger, adequately powered studies are required to clarify survival benefit and identify patients most likely to benefit from PORT.