RADT-10. CEREBELLAR RE-IRRADIATION AFTER WHOLE BRAIN RADIOTHERAPY SIGNIFICANT SYMPTOM RELIEF WITH MINIMAL TOXICITY IN METASTATIC BRAIN PATIENTS

Abstract INTRODUCTION Whole-brain irradiation (WBRT) remains a standard treatment for patients with extensive brain metastases, providing symptom relief and prolonging survival. However, patients often experience recurrent metastases, necessitating re-irradiation. This study evaluates the efficacy and safety of cerebellar-only re-irradiation for improving symptoms and reducing toxicity in patients with recurrent cerebellar metastases following WBRT. METHODS A retrospective review was conducted on patients who underwent cerebellar re-irradiation between 2017 and 2023 after prior WBRT for symptomatic cerebellar metastases. Clinical, dosimetric, and outcome data were collected. Symptom improvement was assessed based on patient, caregiver, and physician reports three months post-treatment. RESULTS The study included 56 patients with a median age of 53 years. Symptom domains included gait dysfunction, nausea/vomiting, dysarthria, movement disorder, dizziness, and headache. Breast cancer was the most common histology. The median interval from WBRT to cerebellar re-irradiation was 15 months. Symptomatic improvement was observed in 75% of patients, with notable improvements in nausea/vomiting (84.6%) and headache (80%). Age, dose deliver and time from WBRT were significant for clinical improvement. Dexamethasone use decreased in 76.3% of patients post-treatment. Radiological responses correlated with clinical improvements in 90% of cases. Only one patient developed symptomatic radiation necrosis. Six-month overall survival and progression-free survival were 50% and 39.2%, respectively. CONCLUSION Cerebellar-only re-irradiation is an effective and safe option for managing recurrent cerebellar metastases, significantly improving symptoms with minimal toxicity. This approach also allows for subsequent systemic therapy or radiosurgery for supratentorial lesions, potentially reducing the need for additional WBRT. Further studies are required to validate these findings in larger cohorts.