Our next speaker will be Dr. Stark from the University of Miami. Thanks very much. So stereotactic radiotherapy has been a treatment for AVMs for over 40 years now. And advancements have occurred in a variety of areas. And treatment pathways have also changed over time as part due to patient referrals and also selection of patients based on AVM and patient characteristics. And so we, in this study, are looking at how stereotactic radiosurgery's outcomes have changed over time. So over time, there have been different models, different planning strategies, and as well, better targeting and multimodality targeting strategies. So in this multicenter study, we analyzed the outcomes of patients in the International Gamma Knife Research Foundation from eight different centers from 1988 to 2014 and divided the cohort in half based on an early cohort versus the modern cohort from 2001 to 2014. And we were looking at the following endpoints, including obliteration, radiation-induced changes, and favorable outcome as defined by obliteration with no hemorrhage and no permanent or symptomatic radiation-induced changes. Looking at the stereotactic radiosurgery parameters in the early versus the late era, we see that over time, there was a significant decrease in margin dose, an increase in maximum dose, the isodose line decreased, and the number of isocenters significantly increased over time in part due to better dosing strategies. We can see here over time, the margin dose significantly decreased over time. Additionally, overall, AVM volume increased with time as more patients with larger AVMs were treated. Speaking of overall outcomes, we can see here there was a significant decrease in obliteration over time from approximately 65 percent to 51 percent. The other complication outcomes, including post-treatment hemorrhage and radiographic-induced changes, were not significantly between the two cohorts. There was an overall decrease in favorable outcome, again, primarily due to decreases in overall obliteration rates. And you can see there was also a significant difference as far as overall outcome approximately eight years in the early era versus almost four years in the late era, as would be expected. So again, in the early era, overall obliteration approximately 65 percent versus 51 percent. In multivariate analysis, early era was a significant predictor of overall obliteration. Again, looking at the other outcomes, there was no difference in post-treatment hemorrhage or radiographic or symptomatic or permanent radiation-induced changes. Again, the early era had a significant increase in overall favorable outcome. And this was only significant in univariate analysis. But in multivariate analysis, when controlling for other factors like AVM size, eloquence, and other factors, overall, the era was not a predictor of long-term favorable outcome. So the number of limitations with this study, including the retrospective analysis, the patient and selection bias, and as well the differences over time in technology and treatments. So in conclusion, despite advances in stereotactic radiosurgery technology, refinement of AVM selection, and contemporary multimodality AVM treatment, we failed to observe substantial improvements in favorable outcome or obliteration rates over time. Differences in patient and treatment parameters may partially account for the significantly lower obliteration rates in the modern era, specifically the treatment of larger AVMs over time. And going forward, improvements in patient selection and dose planning are necessary to optimize our contemporary and modern outcomes. I have to thank a lot of people that contributed to this, all the members of the International Gamma Knife Research Foundation. Thanks very much. Thank you.

Dr. Stark

University of Miami

stereotactic radiosurgery

arteriovenous malformations

International Gamma Knife Research Foundation