Impacts of new agents for multiple myeloma on development of secondary myelodysplastic syndrome and acute myeloid leukemia.

The use of new agents (NAs) such as bortezomib, thalidomide, and lenalidomide has extended the survival of patients with multiple myeloma (MM). However, whether long-term treatment using NAs may increase the risk of second primary malignancies is a concern. Three hundred and thirty-three patients with MM were treated at our hospital from 1998 to 2013. Additional chromosomal abnormalities (CAs), associated with secondary myelodysplastic syndrome/acute myeloid leukemia, were observed in 13 of 152 users of NAs, but in 38 of 181 non-users of NAs. The cumulative CA incidence was higher in non-users of NAs. The CAs frequently observed were 13q-, 20q-, +8 in users of NAs, while -5/5q- and -7/7q- were detected in non-users of NAs. The total dose and treatment period of NAs did not differ between CAs-positive and -negative patients. However, a higher dose of melphalan was observed to have been used in patients who had CAs. Longer follow-up periods are necessary for an accurate risk assessment.