Vascular cancerous embolism refers to the formation of emboli by cancer cells that dislodge into blood vessels and block them. The embolus formed by cancer cells can flow all over the body with the blood system, and can block cerebral artery, pulmonary artery, lower limb artery, renal artery, etc., which may be life-threatening when it causes ischemia and infarction of vital organs. The blockage of cerebral artery by cancer embolus may cause cerebral infarction, which may be manifested as hemiplegia (inability to move one side of the limb freely), slow reaction or coma. Blockage of pulmonary artery may cause sharp decline in respiratory and circulatory functions; blockage of lower limb artery may cause necrosis of limbs; blockage of renal artery may cause renal ischemia, which may be manifested as oliguria, hematuria, and so on. Patients with cancer who suddenly have symptoms of embolism may be caused by cancer embolism, patients should consult the doctor in time, do not take medicine by themselves, but be treated under the guidance of physician.