A new staging system to predict prognosis of patients with multiple myeloma in an era of novel therapeutic agents

Various prognostic markers for multiple myeloma (MM) have been identified, and stratification using these markers is considered important to optimize treatment strategies. The international staging system (ISS) is now a widely accepted prognostic staging system for MM patients; however, its validity is controversial in the era of new therapeutic regimens, since ISS had been established before introduction of new agents. We retrospectively reviewed prognostic factors in order to seek out an alternative staging system more suitably applied to MM patients treated with novel agents. We analyzed 178 newly diagnosed MM patients who received either conventional chemotherapy without novel agents (CT; n = 79) or chemotherapy with novel agents (NT; n = 99). Although median overall survival (OS) of patients treated with CT is significantly different depending on stages of ISS, ISS had no effect on OS among patients treated with NT. Meanwhile, we identified hemoglobin (Hb) and plasmacytoma as independent risk factors for OS in patients who received NT. Using these two parameters, we stratified NT patients into three stages; stage 1 (Hb≥10 g/dL and absence of plasmacytoma), stage 2 (not stage 1 or 3), and stage 3 (Hb <10 g/dL and presence of plasmacytoma). We found that there were significant differences in median OS among the three stages (8.13, 5.95, and 2.45 yr for stages 1, 2, and 3, respectively). This preliminary study suggests that this alternative staging system based on Hb and plasmacytoma is a simple and useful way to predict prognosis of MM patients in the novel agent era.