Revised MALT-IPI: A new predictive model that identifies high-risk patients with extranodal marginal zone lymphoma.

Extranodal marginal zone lymphoma (EMZL) is a heterogeneous disease with a subset of patients exhibiting a more aggressive course. We previously reported that EMZL with multiple mucosal sites (MMS) at diagnosis is characterized by shorter survival. To better recognize patients with different patterns of progression-free survival (PFS) we developed and validated a new prognostic index primarily based on patient's disease characteristics. We derived the "Revised mucosa-associated lymphoid tissue International Prognostic Index" (Revised MALT-IPI) in a large data set (n=397) by identifying candidate variables that showed highest prognostic association with PFS. The revised MALT-IPI was validated in two independent cohorts, from the University of Iowa/Mayo Clinic (n=297) and from IELSG-19 study (n=400). A stepwise Cox regression analysis yielded a model including four independent predictors of shorter PFS. Revised MALT-IPI has scores ranging from 0 to 5, calculated as a sum of 1 point for each of the following- age >60 years, elevated LDH, and stage III-IV; and 2 points for MMS. In the training cohort, the Revised MALT-IPI defined 4 risk groups: low risk (score 0, reference group), low-medium risk (score 1, HR=1.85, P=0.008), medium-high risk (score 2, HR=3.84, P<.0001), and high risk (score 3+, HR=8.48, P<.0001). Performance of the Revised MALT-IPI was similar in external validation cohorts. Revised MALT-IPI is a new index centered on disease characteristics that provides robust risk-stratification identifying a group of patients characterized by earlier progression of disease. Revised MALT-IPI can allow a more disease-adjusted management of patients with EMZL in clinical trials and practice. This article is protected by copyright. All rights reserved.