Background: Cryptogenic stroke is relatively common in patients with active cancer. We aimed to evaluate the association between neutrophil ratio and cryptogenic stroke in patients with acute ischemic stroke and active cancer.
Methods: A retrospective study was conducted at Kyungbook National University Chilgok Hospital, which is a university hospital with comprehensive stroke and cancer centers. We included patients with acute ischemic stroke and active cancer between January 2016 and September 2018. Cryptogenic stroke was defined as a cerebral infarction not attributed to a definite source of cardioembolism, large-vessel atherosclerosis, or small-vessel disease according to The Trial of Org 10172 in Acute Stroke Treatment. We assessed the association of neutrophil ratio with cryptogenic stroke.
Results: Among 51 enrolled patients, cryptogenic stroke developed in 22 patients. In univariate analyses revealed that neutrophil ratio (OR 1.05; 95% CI 1.01-1.10) and systemic metastasis (OR 4.82; 95% CI 1.39-16.66) were associated with increased risk of cryptogenic stroke. Neutrophil ratio independently predicted cryptogenic stroke after adjustment of age, sex, and systemic metastasis. 
Conclusions: This study demonstrated that high level of neutrophil ratio was associated with cryptogenic stroke in patients with acute ischemic stroke and active cancer. Further large prospective studies are warranted.

NEUTROPHIL RATIO IS ASSOCIATED WITH CRYPTOGENIC STROKE IN PATIENTS WITH ACUTE ISCHEMIC STROKE AND ACTIVE CANCER