Ambulatory Care Cause of Death Fibrinolytic Agents--therapeutic use Hemorrhage--chemically induced Heparin, Low-Molecular-Weight--therapeutic use Humans Lung Neoplasms--drug therapy Neoplasms--drug therapy Pancreatic Neoplasms--etiology Primary Prevention Pulmonary Embolism--etiology Randomized Controlled Trials as Topic Venous Thromboembolism--etiology Venous Thrombosis--etiology