PQA 04 - PQA 04 Palliative Care and Central Nervous System Poster Q&A
2632 - Biological Effective Dose-Based Fractionated Stereotactic Radiation Therapy for Brain Metastasis in the New Era: A Retrospective Multi-Institution Study
Kumamoto University Kumamoto 860-8556, kumamoto city
T. Watakabe; Department of Radiation Oncology, Kumamoto University Hospital, Kumamoto, Japan
Purpose/Objective(s): Considering advancements in systemic cancer therapies, this research aims to reassess the efficacy and safety of BED-based FSRT in managing NSCLC brain metastases. The study evaluates local control rates and the incidence of radiation-induced brain necrosis, comparing these outcomes to our previous data to determine if BED-based FSRT remains a viable option in modern oncologic care.Materials/
Methods: A retrospective analysis was conducted on 670 consecutive NSCLC patients with 1823 brain metastases treated at two institutions between April 2009 and December 2020. BED-based FSRT was administered using Liniac, with dose fractionation adjusted according to size so that peripheral BED10 would be approximately 70-90 Gy. The peripheral dose was approximately 80-90% of the maximum dose, and 95% of the PTV (D95) was covered by the peripheral dose. The evaluation of treatment outcomes included local control, overall survival, and the incidence of brain necrosis, employing Kaplan-Meier survival analysis for statistical assessment.
Results: The median peripheral BED10 was established at 82 Gy (40-137 Gy) across a median of 3 fractions (range, 1-14). The median tumor diameter was 7 mm (2-59 mm). The median overall survival was 30.7 months. The local control rates at one, two, and five years with BED-based FSRT were 98.3%, 97.5%, and 96.2%, respectively. The incidence of brain necrosis at one, two, and five years was 2.4%, 5.6%, and 14.8%, respectively. These findings highlight that BED-based FSRT can provide effective local control with an acceptable risk of adverse effects in the new era.
Conclusion: The study validates the hypothesis, showing that FSRT with a consistent BED can achieve adequate local control and favorable toxicity profiles for NSCLC brain metastases in the current era of cancer treatment. These outcomes affirm the relevance of BED-based FSRT as a key component in the multimodal management of brain metastases, advocating for its continued application alongside evolving systemic therapies.
