Discovery of New Cancer in the 1-year Follow-up After Ischemic Stroke in Patients at Risk: The INVISIBLE-1 Study

Inclusion Criteria: * Informed consent as documented by signature from patient or next of kin * Age ≥ 18 years old * Acute ischemic stroke with symptom onset within 48 h before admission * Acute ischemic stroke with: * persistent signs and symptoms of stroke lasting for ≥ 24 hours OR * acute brain infarction documented by computer tomography (CT) or MRI * D-dimer ≥ 820 μg/L measured after symptom-onset and within 24h after admission * Embolic stroke of unknown source (ESUS)\* after initial work-up (acute cerebral imaging, 12-lead electrocardiogram, cardiac monitoring for at least 24h and echocardiography) Exclusion Criteria: * Active cancer\*\* known at time of index-stroke * Intravenous Thrombolysis administrated prior to D-dimer measurement: Use of external laboratory value possible if available * New diagnosis of central nervous system cancer * Patient or next of kin (in case of lacking capacity) unlikely to be compliant or available for study follow-up interview ESUS\*: According to the definition from the NAVIGATE ESUS randomized trial: Non-lacunar ischemic stroke occurring in a patient in whom investigations did not show another specifically treatable underlying stroke etiology, primarily \>50% stenosis in a proximal extracranial or intracranial artery, atrial fibrillation, other major-risk cardioembolic sources, or other determined etiology. Active Cancer\*\*: According to the definition from the International Society on Thrombosis and Haemostasis: Cancer dia…