Low incidence of thromboembolism in relapsed/refractory myeloma patients treated with thalidomide without thromboprophylaxis in Taiwan

Thromboembolism(TE) is a common complication in patients withmultiple myeloma (MM). Immunomodulatory agents, e.g., thalidomide, have expanded the therapeutic options for treating myeloma; however, Western countries report a high incidence of thrombosis in thalidomide-treated MM patients who lack thromboprophylaxis. A Korean trial reported low TE incidence in thalidomide-treated myeloma patients (39 % were given aspirin prophylactically).We aimed to elucidate the TE frequency in MM patients in Taiwan who were treated with thalidomide without TE prophylaxis. We retrospectively collected the records of MM patients who had used thalidomide from a single institute between 2004 and 2010, combined these records with two other Taiwanese studies, and compared all three with the Korean trial. In the current Taiwanese series, five of 144 patients (3.5%) developed TE as follows: three (2.1 %) were venous and two (1.3 %) were arterial. Only 6.1 % of the patients had undergone TE prophylaxis, which is less than in the Korean trial (38.9 %, p<0.05). Of the patients in the relapsed/refractory cohort (n=114) who were given thalidomide alone, none (0/52) developed venous TE (VTE); however, two patients (2/35, 5.7 %) who were given thalidomide-dexamethasone as a salvage treatment developed VTE. In the thrombosis cohort, four patients (80 %) were treated with thalidomide plus dexamethasone. In conclusion, the frequency of thalidomide-related TE in myeloma patients without effective TE prophylaxis was low in Taiwan. In relapsed/refractory myeloma patients, the VTE frequency was slightly lower compared with Western patients irrespective of treatment with thalidomide alone or combined with dexamethasone. Even in low TE incidence areas, thalidomide combined with dexamethasone was more thrombogenic compared with others.