Clinical characteristics and outcomes of patients newly diagnosed with multiple myeloma with extramedullary disease

Objective: To compare the clinical characteristics and outcomes of patients newly diagnosed with multiple myeloma(NDMM)with bone-related extramedullary(EM-B)disease and those with extraosseous extramedullary(EM-E)disease and to address their prognostic factors. Methods: The clinical features, outcomes, and prognostic factors were retrospectively analyzed in 80 patients with NDMM with extramedullary disease. Results: Among 80 patients with extramedullary disease, 51 had EM-B and 29 EM-E. The level of β(2)-microglobulin(5.82 mg/L vs 3.99 mg/L, P=0.030), lactate dehydrogenase(256 U/L vs 184 U/L, P=0.003), 1q21 amplification rate(78.6% vs 53.1%, P=0.035), and Ki-67 proliferation index(50% vs 25%, P=0.002)in the EME group were significantly higher than those in the EM-B group. The posieive rate of CD56(14.3% vs 66.7%)and overall response rate(60% vs 82.3%)in EM-E group were significantly lower than those in EM-B group. The median overall survival (OS)of patients with EM-E and EM-B was 14.5 and 49.5 months, and the median progression-free survival(PFS)of the two groups was 9.0 and 18.0 months. Patients with EM-E had a significantly shorter OS(P=0.035)and PFS(P < 0.001)than those of patients with EM-B, whereas the PFS did not significantly differ(P=0.263)when patients accepted proteasome inhibitor(PI)-based regimens for induction therapy. Multivariate analysis with Cox model showed the best response that did not achieve partial response(PR)was an independent poor prognostic factor for both OS and PFS in NDMM patients with EM-E(P=0.031, P=0.005), ISS-III, and the best response that did not achieve PR were independent prognostic factors for the shorter OS in patients with NDMM with EM-B(P=0.009, P=0.044). Conclusions: The clinical characteristics and outcomes of patients with NDMM with EM-E are different from patients with EM-B. Outcomes of patients with EM-E is significantly poor. PI induction therapy improved the PFS of patients with EM-E.