Evaluation of Revised International Staging System (R-ISS) for transplant-eligible multiple myeloma patients

The International Myeloma Working Group has proposed the Revised International Staging System (R-ISS) for risk stratification of multiple myeloma (MM) patients. There are a limited number of studies that have validated this risk model in the autologous stem cell transplant (ASCT) setting. In this retrospective study, we evaluated the applicability and value for predicting survival of the R-ISS model in 134 MM patients treated with new agents and ASCT at the Mayo Clinic in Arizona and the University Hospital of Salamanca in Spain. The patients were reclassified at diagnosis according to the R-ISS: 44 patients (33%) had stage I, 75 (56%) had stage II, and 15 (11%) had stage III. After a median follow-up of 60 months, R-ISS assessed at diagnosis was an independent predictor for overall survival (OS) after ASCT, with median OS not reached, 111 and 37 months for R-ISS I, II and III, respectively ( P < 0.001). We also found that patients belonging to R-ISS II and having high-risk chromosomal abnormalities (CA) had a significant shorter median OS than those with R-ISS II without CA: 70 vs. 111 months, respectively. Therefore, this study lends further support for the R-ISS as a reliable prognostic tool for estimating survival in transplant myeloma patients and suggests the importance of high-risk CA in the R-ISS II group.