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 diagnosed within the previous six months, recurrent, regionally advanced or metastatic cancer, cancer for which treatment had been administered within six months, or hematological malignancy that is not in complete remission for more than 5 years. ► Patients with history of cancer not meeting these criteria anymore can be included in the study.