Radiotherapy is often used in the management of primary brain tumors, but late cerebrovascular risks remain incompletely characterized. We examined the relationship between radiotherapy and the risk of death from cerebrovascular disease (CVD) in this population. We used the Surveillance, Epidemiology, and End Results Program to identify 19,565 patients of any age diagnosed with a primary brain tumor between 1983-2002. Multivariable competing risks analysis and an interaction model were used to determine whether receipt of radiotherapy was associated with an increased risk of CVD-specific death, adjusting for tumor proximity to central arterial circulations of the brain. The median follow up in surviving patients was 12.75 years. Baseline characteristics were similar in patients who did and did not receive radiotherapy. Ten-year CVD-specific mortality in patients with tumors near central arterial circulations who did and did not receive radiotherapy were 0.64 % (95 % CI 0.42-0.93 %) versus 0.16 % (95 % CI 0.055-0.40 %), p = 0.01. After adjustment for demographic, tumor-related, and treatment-related covariates, patients with tumors near central arterial circulations were significantly more likely to experience CVD-specific mortality after radiotherapy (HR 2.81; 95 % CI 1.25-6.31; p = 0.01); no association was observed among patients with more distant tumors (HR 0.77; 95 % CI 0.50-1.16; p = 0.21). The interaction model showed that tumor location was a key predictor of the risk of radiotherapy-associated, CVD-specific mortality (p-interaction = 0.004). Patients receiving radiotherapy for tumors near but not distant from the central vasculature of the brain are at increased risk for death secondary to CVD, which should be considered when counseling patients.
Keywords: Cancer; Death; Location; Radiation; Stroke.