Thrombophilic state in breast cancer.

Tumor cell metastasis and thrombosis are the major causes of death in cancer patients. Thrombosis in cancer patients may occur when physiologic antithrombotic systems are defective or when prothrombotic activities defeat normal physiologic antithrombotic mechanisms. Malignancies by themselves may already predispose to a hypercoagulable state in cancer patients. Tumor cells can either directly activate the blood clotting system or indirectly stimulate mononuclear cells to synthesize and express various procoagulants, subsequently leading to prothrombin activation, fibrin formation, and generation of a thrombus. In addition, other comorbid predisposing factors effecting thrombosis in cancer patients have to be considered, including surgery, bed rest, infection, long-term indwelling central venous catheters, anticoagulation, and chemotoxic or steroidal anticancer drugs used in adjuvant or palliative cancer treatment. Reliable information on the incidence of thromboembolism in cancer patients is available for breast cancer; less data have been reported for other malignancies. Chemo- and/or hormone therapy in patients with primary or metastatic breast cancer is associated with an increased thromboembolic risk, although the benefits of treatment far outweigh the risks. The current literature discussing the effect of chemo/hormone therapy on blood clotting factors and the associated risk of thrombosis is reviewed, with emphasis on new developments in the area of tissue-specific SERMs (selective estrogen receptor modulators). SERMs are employed as adjuvant therapy in primary breast cancer and in the palliation of advanced breast cancer and may be clinically useful as potential substitutes for long-term hormone replacement therapy, in the treatment of osteoporosis, and for cancer prevention therapy.