A Prognostic Scoring System for Patients with Multiple Myeloma Who Were Classified Stage II By Revised International Staging System

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Background: Revised International Staging System (R-ISS) is recently proposed risk stratification algorism based on ISS, cytogenetic risk, and lactate dehydrogenase in multiple myeloma (MM). Although R-ISS had an improved prognostic power compared to ISS, there is a problem that patients with stage II increase to 1.7 times. In this study, we evaluated survival outcomes and a new prognostic tool for MM patients classified as R-ISS II.Methods: Retrospective data from 441 patients who were initially treated with a novel agent-containing regimens were analyzed.Results: R-ISS staging system could discriminate survival outcome more clearly compared to ISS in patients treated with novel-agents [median overall survival (OS) times of R-ISS I vs. II. Vs. III was 76.3 vs. 51.3 vs. 30.3 months, P < 0.001]. By applying R-ISS, 6.2% of patients with ISS I, and 24.3% with ISS III were reclassified into R-ISS II. Overall, 290 patients (66%) was classified into R-ISS II and had wide range of survival outcomes (0.7-114.5 months). In multivariate analysis, poor performance status (PS) (HR 1.657, 95% CI 1.159-2.370, P =0.006), del (17p13) (HR 2.227, 95% CI 1.174-4.223), P = 0.014), and thrombocytopenia (HR 1.533, 95% CI 1.033-2.276, P = 0.034) were significantly associated with OS in patients with R-ISS II. Based on this analysis, we constructed a new prognostic model consisted of poor PS (1 point), del(17p13) (2 point), and thrombocytopenia (1point). Among the 290 patients, 152 patients (52.4%) were classified as low-risk (score 0), 109 (37.5%) as intermediate risk (score 1), and 29 (10%) as high risk (scores 2 or more). The median OS times for the corresponding risk groups was 57.5 months (95% CI 40.4-74.5), 30.2 months (95% CI 20.7-39.7), and 20.9 months (95% CI 6.4-35.3) (P <0.001).Conclusion: R-ISS is an excellent prognostic tool in MM in the novel-agent era, but there is a limitation that most of patients were classified into R-ISS II. A new prognostic model for patients with R-ISS II is needed, and prognostic scoring system based on poor PS, del(17p13), and thrombocytopenia may be useful to distinguishing survival outcomes of patients with R-ISS II. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.