Researchers then classified patients into three groups. The revised International Staging System (R-ISS) I group included patients with a serum β2-microglobulin level <3.5 mg/L and a serum albumin level ≥3.5 g/dL, no high-risk chromosomal abnormalities, and a normal lactate dehydrogenase level. Patients in the R-ISS III contained patients with a serum β2-microglobulin level >5.5 mg/L and high-risk chromosomal abnormalities or a high lactate dehydrogenase level. R-ISS II included patients with all other possible combinations.1

High-risk chromosomal abnormalities include del(17p) and/or t(4;14) and/or t(14;16).1


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“This is the first approach that put together tumor mass (ISS) and biology of disease. Other papers did this, but we wanted to have a standard to incorporate in clinical trials, otherwise it is difficult to compare different studies,” Dr. Palumbo said.

Results showed that at a median follow-up of 46 months, patients in the R-ISS I group had a 5-year overall survival rate of 82% compared with 62% in the R-ISS II and 40% in the R-ISS III groups. The 5-year progression-free survival rates were 55%, 36%, and 24% in the R-ISS I, R-ISS II, and R-ISS III groups, respectively.1

Of note, 95% of patients in this study received novel agents;1 however, “novel therapies mainly improved standard-risk patients,” Dr. Palumbo said. “Very little benefit has been shown in high-risk patients” with novel agents like carfilzomib.

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The findings suggest that the revised ISS should be used in future clinical studies to effectively stratify patients with newly diagnosed multiple myeloma by their relative risk for survival.1

“We finally have a standard that incorporates both tumor mass and biology of tumor, which will allow us to compare subgroups among different studies,” Dr. Palumbo concluded.

Reference

  1. Palumbo A, Avet-Loiseau H, Oliva S, et al. Revised International Staging System for multiple myeloma: a report from International Myeloma Working Group. J Clin Oncol. 2015. [epub ahead of print]. doi: 10.1200/JCO.2015.61.2267.
  2. “What are the key statistics about multiple myeloma?” American Cancer Society website. Updated March 9, 2015. http://www.cancer.org/cancer/multiplemyeloma/detailedguide/multiple-myeloma-key-statistics. Accessed August 5, 2015.