Impact of extramedullary plasmacytomas on outcomes according to treatment approach in newly diagnosed symptomatic multiple myeloma

The prognostic impact of extramedullary plasmacytomas (EMPs) on newly diagnosed symptomatic multiple myeloma (MM) was evaluated in the context of treatment approach including autologous stem cell transplantation (ASCT) and chemotherapy alone. A total of 275 consecutive patients with newly diagnosed MM were included, and 54 patients (19.6 %) had EMPs at diagnosis. Patients with initial EMPs were more likely to have myeloma bone disease but favorable laboratory parameters in hemoglobin and β2-microglobulin. Patients were treated with different schemas based on transplant eligibility (154 in ASCT-eligible vs. 121 in ASCT-ineligible). After a median follow-up of 24.6 months (range, 0.2-56.3 months) in survivors, patients with initial EMPs had significantly worse progression-free survival (PFS) (P = 0.035) and overall survival (OS) (P = 0.006) compared to those without initial EMPs. In the multivariate analyses, the presence of initial EMPs was an independent prognostic factor for PFS (relative risk (RR) of 2.24, P = 0.024) and OS (RR of 2.47, P = 0.027) in the transplant-ineligible patients, whereas it did not significantly influence PFS (P = 0.341) or OS (P = 0.499) in the transplant-eligible patients. However, the adverse impact of EMPs observed in transplant-ineligible patients was attenuated among the patients treated with bortezomib. These data suggest that ASCT can overcome the negative impact of EMPs and highlight the potential efficacy of bortezomib on EMPs in the non-transplant setting.