Comparison of clinical characteristics, treatment efficacy and survival in patients with newly diagnosed multiple myeloma with single- versus multi-site extramedullary invasion.

rISS stage III was possibly associated with poor survival of EMM patients with multi-site invasion or with EM-B. Plasma cell percentage ≥ 20% was associated with poor survival of EMM patients with EM-E. Comparison should not only be done between single- and multi-site invasions, but also between EM-B and EM-E.