Objective Relatively little is known about the effect of malignancy on patient outcomes after acute ischemic stroke (AIS) or utilization rates of stroke interventions in this population. We aimed to assess the effect of underlying malignancy on outcomes and treatment of AIS at a population level.

Methods Outcomes after AIS between patients with and without malignancy were compared using a national database of hospital reported outcomes.

Results There were 351 institutions reporting the outcomes of 3 18 127 admissions for AIS. Of these admissions, 16 141 patients carried a pre-existing diagnosis of malignancy at the time of admission. Administration of intravenous tissue plasminogen activator (IV tPA) was less common in patients with malignancy compared with patients without malignancy (7.3% vs 10.7%; P<0.001) but there was no difference in the rate of mechanical thrombectomy (3.1% vs 3.1%; P=0.967). Mortality rates were higher among patients with malignancy (7.1% vs 3.7%; P<0.001), a relationship which persisted when analysis was restricted to patients receiving IV tPA (10.8% vs 6.1%; P<0.001) or thrombectomy (20.3% vs 13.5%; P<0.001). Rates of both IV tPA administration (2.5% vs 10.5%; P<0.001) and mechanical thrombectomy (2.1% vs 5.4%; P<0.001) were lower in patients with brain malignancy relative to patients with malignancy of non-CNS origin.

Conclusion A diagnosis of malignancy on admission for acute stroke was associated with a higher rate of mortality. Malignancy was also associated with a lower rate of IV tPA administration but no difference in mechanical thrombectomy utilization.