 After any surgery, there is a risk of venous thromboembolism VTE, including Deep Vein Thrombosis DVT in the major veins of the legs and Pulmonary Embolus PE in the lungs. These clots are usually prevented by the administration of low-molecular-weight heparin, a blood thinner that prevents clotting. In most surgical specialties like thoracic or vascular surgery, this treatment is used until patients are discharged from the hospital. However, in orthopaedic surgery, there is strong evidence that longer term preventative treatment up to 35 days after hospital discharge helps to reduce VTE occurrences. In thoracic surgery, there is an even greater risk of developing PE because of the surgical stress, the common presence of cancer and direct damage to blood vessels in the lung during surgery. Despite the potential utility, the use of extended VTE prevention has never been evaluated in the thoracic surgery population. If extended treatment prevents clots, more patients will avoid complications related to VTE. There is currently very limited information available on the incidence of venous thromboembolism VTE in patients undergoing lung cancer resection and the utility of extended thromboprophylaxis ET in this patient population. Furthermore, in contrast to patients undergoing orthopaedic surgery where ET has become standard of care, duration of thromboprophylaxis is not well defined in this patient population. Therefore, there is a clear need to systematically evaluate the effects of extended VTE prophylaxis on the incidence of VTE in the post-op population. 