Some forms of cancer change the clotting characteristics of the blood, which can increase the likelihood of blood clots. Some forms of cancer treatment, including surgery, chemotherapy, and hormone and antibody therapy, can also increase the risk of VTE. Reduced mobility associated with these treatments or because of the effects of the disease can also increase the risk of thrombosis in people with cancer.

DVT and PE are two of the most common complications of cancer. Cancer increases the risk of DVT by four to six times, and a diagnosis of DVT and PE is associated with a higher risk of death in patients with cancer.