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 one point for each of the following‐ age >60 years, elevated LDH, and stage III–IV; and two points for MMS. In the training cohort, the Revised MALT‐IPI defined four risk groups: low risk (score 0, reference group), low‐medium risk (score 1, HR = 1.85, p = .008), medium‐high risk (score 2, HR = 3.84, p