Second primary malignancies in multiple myeloma: A review

As survival times of multiple myeloma (MM) patients continue to improve, second primary malignancies (SPM) have become an increasingly relevant long-term risk among MM survivors. Population studies since the 1950s have consistently observed an increased incidence of hematologic SPMs, specifically acute leukemia, among MM survivors. Prolonged treatment with alkylators, especially melphalan, was associated with an increased hematologic SPM risk; likewise, autologous stem cell transplantation appeared to minimally increase SPM risk. Immunomodulatory drugs, specifically lenalidomide, was associated with an increased SPM incidence, although most studies concluded that the benefits of therapy outweighed any risks of SPM. Newer anti-myeloma therapy such as proteasome inhibitors and monoclonal antibodies did not appear to increase SPM risk although robust long-term follow-up is lacking. This review discusses current understanding regarding SPMs among survivors of MM, how different host-, disease- and treatment-related factors contribute to SPM incidence and highlights emerging screening guidelines and prognosis for SPMs.