NCMP-09. Impact of Tumour Characteristics and Cancer Treatment on Cerebrovascular Mortality After Glioma Diagnosis: Evidence From a Population-Based Cancer Registry

Abstract

BACKGROUND Brain tumour patients have the highest stroke mortality rates among cancer types, but the factors associated with fatal stroke remain unknown. We aimed to examine to what extent brain tumour grade, a marker of biological aggressiveness, tumour size and cancer treatment are associated with cerebrovascular mortality among patients with malignant glioma, the most common and aggressive brain tumour. METHODS We conducted a retrospective, observational cohort study using the US National Cancer Institute’s state and regional population-based cancer registries (NCI SEER). We identified adult patients with a diagnosis of malignant glioma (2000 to 2018, Nf72,916). The primary outcome of interest was death from cerebrovascular disease. Cox regression modelling estimated the associations with cerebrovascular mortality of tumour grade, tumour size and treatment (surgery, radiotherapy, chemotherapy), calculating hazard ratios (HR) adjusted for these factors as well as for age, sex, race, marital status and calendar year. RESULTS Higher grade (Grade IV vs Grade II: HR=2.47, 95% CI=1.69-3.61, p< 0.001) and larger brain tumours (size 3 to < 6 cm: HR=1.40, 95% CI=1.03 -1.89, p< 0.05; size ≥ 6 cm: HR=1.47, 95% CI=1.02-2.13, p< 0.05 compared to size < 3cm) were associated with increased cerebrovascular mortality. Having cancer treatment was associated with decreased risk (surgery: HR= 0.60, p< 0.001; chemotherapy: HR=0.42, p< 0.001; radiation: HR= 0.69, p< 0.05). However, among patents surviving five years or more from their cancer diagnosis radiotherapy was associated with higher risk of cerebrovascular mortality (HR 2.73, 95% CI 1.49-4.99, p< 0.01). CONCLUSIONS More aggressive tumour characteristics are associated with increased cerebrovascular mortality, and treatment was associated with lower risk within 5 years of diagnosis. Radiotherapy increased risk of fatal cerebrovascular outcome five-years after cancer diagnosis. Further research is needed to better understand the long-term cardiovascular consequences of radiation therapy, and whether the consequent risk can be mitigated.