Introduction: Radiosurgery has been shown as an effective definitive treatment for brain AVMs. However, for patients with residual AVMs after a single radiosurgery treatment, the benefit of receiving additional radiosurgery treatments is less clear. In this study, we aim to determine the comparative outcome of multiple radiosurgery procedures.
Methods: We retrospectively reviewed patients with brain AVMs from 1990-2015 at our institution. Three groups of patients were included: conservative management(CS), single radiosurgery(SR), and multiple radiosurgery(MR). We included treatment-propensity-related variables determined through univariable analysis into propensity-score-matching. MR was consecutively matched to other two groups in approximately 1:2 ratio. The matched groups were combined and examined in univariable analysis to test for balance. Patient outcomes were then compared.
Results: Younger patients with larger AVMs and deep drainage were more likely to receive MR. There were 35 patients in MR, and 51 were matched in SR and 44 matched in CS; therefore, our cohort consisted of 130 patients. There was no significant difference in distribution of baseline variables(p>0.05) between different treatment groups. The average total dose received was 2760.0cGy and 2074.4cGy respectively for MR(n=30) and SR(n=43). More hemorrhages occurred during the follow-up period in the MR(14.3%) than in SR(2.0%,p=0.039) group, compared to 31.8% in conservative management(p<0.001). Of note, all follow-up hemorrhages in MR occurred between first and second treatment. Although no difference in overall obliteration(43.1% versus 45.7%,p=0.937) was found, 60% who hemorrhaged in MR experienced eventual obliteration. No difference in last follow-up mRS(p=0.653) was found between SR and MR.
Conclusions: Additional radiosurgery for patients with residual AVMs after first radiosurgery should be considered on individual basis. For patients with hemorrhage after initial radiosurgery, additional radiosurgery may achieve obliteration and prevent further hemorrhage. However, for patients without post-treatment hemorrhage, it is less clear whether receiving additional treatment will benefit the patient within the context of obliteration and functional outcome.
Patient Care: We found no substantial evidence that additional radiosurgery for unobliterated patient without hemorrhage at follow-up will further benefit patient by obliteration. This finding warrants further investigation and if confirmed may potentially change pattern of care for AVM patients who have already underwent radiosurgery
Learning Objectives: By the conclusion of this session, participants should be able to:
1. Understand the differences in post-treatment hemorrhagic rates between patients receiving single and multiple session radiotherapy
2. Appreciate the effect of post-treatment hemorrhage on AVM obliteration rate
3. Appreciate the factors to consider in deciding single versus multiple session radiotherapy