Outcomes of patients with POEMS syndrome treated initially with radiation.

POEMS syndrome is a rare plasma cell dyscrasia presenting with polyneuropathy and other systemic findings. Patients with 1 to 3 bone lesions and negative bone marrows are often treated with involved field radiation therapy as the initial and potentially definitive therapy. Long-term outcomes of patients treated with this approach have not been systematically studied. Of the 146 patients with POEMS syndrome seen at the Mayo Clinic between January 1999 and September 2011, 38 (26%) were given targeted radiation as their initial primary therapy and are the ones studied here. The median number of bone lesions was 1 (range: 1-6). The median dose of radiation administered was 45 Gy (range: 35-54 Gy). Complete or partial hematologic, vascular endothelial growth factor, fluorodeoxyglucose-positron emission tomography, and clinical responses were documented in 31%, 14%, 22%, and 47%, respectively. With median follow-up of 43 months, the 4-year overall survival is 97% and event-free survival is 52%. Risk factors for needing salvage therapy included reduced pulmonary diffusing capacity of carbon monoxide and increased urinary total protein. The presence of 3 lesions compared with 1 or 2 did not increase risk for treatment failure. Among selected patients with POEMS syndrome, radiation produces durable, meaningful responses.