Subsequent primary malignancies among multiple myeloma patients treated with or without lenalidomide.

Risk of subsequent primary malignancies (SPMs) associated with lenalidomide therapy in multiple myeloma (MM) patients, outside the context of melphalan-based therapy is not established. We assessed the risk of SPMs in lenalidomide treated MM patients (n = 1653) at Moffitt Cancer Center (2004-2012) outside the context of melphalan-based induction therapy and post-melphalan maintenance therapy, via (1) cohort analysis and (2) nested case-control study. Incident SPMs (n = 51) were matched to controls (n = 102) on age at MM diagnosis, gender, follow-up time, and date of diagnosis. Incidence of SPM differed significantly (p = 0.0038) between MM patients treated with and without lenalidomide (5-year incidence estimates of 3.2 and 6.2%, respectively), although not significant after adjustment for age and year of diagnosis (HR = 0.82, 95%CI = 0.43-1.57). Lenalidomide treatment was inversely associated with SPM in the nested case-control analysis (OR = 0.03, 95%CI = 0.002-0.34). In this large cohort of MM patients, lenalidomide treatment was not associated with an increased risk of SPM.