Impact of extramedullary disease in patients with newly diagnosed multiple myeloma undergoing autologous stem cell transplantation: A study from the Chronic Malignancies Working Party of the EBMT

We investigated extramedullary disease in newly diagnosed multiple myeloma patients and its impact on outcome following first line autologous stem cell transplantation. We identified 3744 adult myeloma patients who received upfront single (n = 3391) or tandem transplantation (n = 353) between 2005 and 2014 with available data on extramedullary in-volvement at diagnosis. The overall incidence of extramedullary disease was 18.2% (n = 682) and increased per year from 6.5% (2005) to 23.7% (2014). Paraskeletal involvement was found in 543 (14.5%) and extramedullary organ involvement in 139 (3.7%) while the majority of 3062 (81.8%) patients had no extramedullary disease. More patients with extramedul-lary organ involvement had multiple involved sites (≥2;) (p