Cerebrovascular events during treatment for systemic malignant tumors in patients with moyamoya disease

With the increasing incidence of malignancies, the importance of cancer-associated stroke (CAS) is emphasized. Although moyamoya disease is a leading cause of stroke, no reports have documented CAS in patients with this condition. We aimed to investigate cerebrovascular events during malignancy treatments in patients with moyamoya disease. A total of 405 patients with moyamoya disease who visited our hospital between January 2000 and March 2022 were retrospectively examined. We evaluated the management of moyamoya disease, presence of the RNF213 p.Arg4810Lys variant, treatments for malignant tumors, presence of cerebrovascular events during treatment and follow-up periods and outcomes. Among the 405 patients, 17 with moyamoya disease (4.2%) were diagnosed with malignancies. Among patients aged 60 years and over, 7 out of 67 (10.4%) had malignancies. Of the 17 patients, 11 (64.7%) were symptomatic, and seven (41.2%) had revascularization surgery. Nine patients were treated with oral antiplatelet drugs. There was no significant difference between the groups with and without malignancy regarding the presence of the RNF213 p.Arg4810Lys variant (80.0% vs 62.7%, p=0.33). All patients underwent surgical treatment and seven (41.2%) received chemotherapy. One death due to tumor progression was reported. No cerebrovascular event was observed during malignancy treatments and follow-up periods, which had a mean duration of 6 years. In our cohort, malignancy treatments in patients with moyamoya disease were safely conducted without cerebrovascular events. However, it is advisable to avoid hypotension, dehydration, hyperventilation, and long-term discontinuation of antiplatelet drugs during treatment of malignant tumors.