The study of the relationship between malignancy and thromboembolic disease is highly relevant. Hypercoagulable state is commonly seen in patients with malignancy, and tumor cells can directly activate coagulation pathways, induce the production of procoagulant substances, and inhibit the anticoagulant activity of vascular endothelial cells, platelets, monocytes, and macrophages. A patient in our department had a sudden onset of deep vein thrombosis in the left lower extremity. The patient had abdominal pain and wasting in the past and was not diagnosed in a hospital in Beijing. It was found to be inoperable. Prince Fan, Department of Vascular Surgery, First Affiliated Hospital of Zhengzhou University Among malignant tumors, pancreatic cancer and thrombosis are closely related, and for those without other risk factors for thrombosis, it is best to exclude the possibility of malignant tumors.