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International Myeloma Working Group Defines Revised International Staging System for Multiple Myeloma

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Key Points

  • A revised International Staging System (ISS) including chromosomal abnormalities and lactate dehydrogenase level is recommended for use in stratifying patients in future clinical trials.
  • Five-year overall survival was 82% in the R-ISS I, 62% in the R-ISS II, and 40% in the R-ISS III groups.

As reported in the Journal of Clinical Oncology by Palumbo et al, the International Myeloma Working Group recommends the use of a revised international staging system (R-ISS) for newly diagnosed multiple myeloma that incorporates chromosomal abnormalities detected by interphase fluorescent in situ hybridization after CD138 plasma cell purification and serum lactate dehydrogenase (LDH) level.

Revised System

In an analysis including 3,060 newly diagnosed  patients from 11 international trials for whom ISS, chromosomal abnormality, and LDH data were available, three R-ISS stages were defined: R-ISS I (n = 871) = ISS stage I (serum β2 microglobulin < 3.5 mg/L and serum albumin ≥ 3.5 g/dL), no high-risk chromosomal abnormality [del(17p) or t(4;14) or t(14;16)], and normal LDH level (< upper limit of normal range); R-ISS III (n = 295) = ISS stage III (serum β2 microglobulin > 5.5 mg/L) and high-risk chromosomal abnormality or high LDH level; and R-ISS II (n = 1,894) = all other possible combinations.

At median follow-up of 46 months, 5-year overall survival was 82% in the R-ISS I, 62% in the R-ISS II, and 40% in the R-ISS III groups, and 5-year progression-free survival was 55%, 36%, and 24%, respectively. Hazard ratios for mortality were 3.68 for R-ISS stage II vs I and 9.95 for stage III vs I. Hazard ratios for disease progression were 1.64 for R-ISS stage II vs I and 2.18 for stage III vs I.

The investigators concluded: “The R-ISS is a simple and powerful prognostic staging system, and we recommend its use in future clinical studies to stratify patients with newly diagnosed multiple myeloma effectively with respect to the relative risk to their survival.”

Antonio Palumbo, MD, of the University of Torino, is the corresponding author of the Journal of Clinical Oncology article.

For full disclosures of the study authors, visit jco.ascopubs.org.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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