**4.2.1 Malignancies and VTE**

More recently, increased plasma homocysteine concentration has been postulated as a risk factor for cancer and even as a novel tumor marker (Sun et al., 2002). Patients with malignancies often have an increased risk of VTE disease and as such being the second most common cause of death in cancer patients, second to the primary disease itself (Rickles et al., 1992). In 1865 Trousseau described hypercoagulability and increasing risk of »spontaneous coagulation« in patients with cancer (Trousseau, 1865). Nowadays, it is established that breast, pancreas, and gastrointestinal cancers are associated with a higher incidence of thrombosis. With more advanced stages of cancer there is a lower overall survival rate, but, also a greater risk of venous thromboembolism, additionally influencing the survival of patients.

The associated pathophysiology of VTE and malignancies has not been precisely defined. However, it has been reported that cancer patients show increased levels of several procoagulant factors (Falanga et al., 1993). It is well established that women with advanced breast cancer show hyperhomocysteinemia, which explains the hight rate of venous thrombosis in women with metastatic breast malignancy (Smith et al., 2008). Other established contributors to the VTE increased risk are: chemotherapy, hormonal adjuvant therapy, surgery, central venous catheters, immobility and inherited thrombophilia, with the notion that oncological therapies do influence the immunological response.
