Thrombotic complications of myeloma therapy

Patients with multiple myeloma are at relatively high baseline risk of developing thromboembolic events (TEE), usually deep vein thromboses. There are numerous contributing factors, among them certain treatment regimens that include thalidomide or related compounds such as lenalidomide combined with glucocorticoids and/or cytotoxic chemotherapy. The risk of developing TEE appears to be particularly high when these immunomodulatory agents are combined with anthracyclines as treatment of newly-diagnosed disease. Up-front combinations including thalidomide plus pulse dexamethasone and/or alkylating agents are associated with an intermediate risk, whereas the same regimens for relapsed/refractory myeloma seem to be associated with the lowest risk. Several different thromboprophylaxis strategies have been effective in lowering the risk of developing clots: daily aspirin (81-325 mg/day), full-intensity warfarin (INR 2-3), and prophylactic enoxaparin (40 mg SQ daily). Low, fixed-dose warfarin may also reduce the risk of TEE, but the data on this are disputable. None of these TEE prevention strategies have been prospectively compared head-to-head, so the choice often reflects physician and/or patient preferences. The available evidence upon which one might make such a decision is reviewed here.