A MALT lymphoma prognostic index

There are no widely accepted prognostic indices for extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma). This study aimed to develop and validate a specific prognostic tool to personalize and optimize lymphoma treatment of patients with MALT lymphoma. A prognostic index was built by Cox regression (stepwise selection) using data from 401 patients enrolled in the international randomized IELSG-19 trial (NCT 00210353). A validation set, including 633 patients, was obtained by merging three independent cohorts of MALT lymphoma patients. The three individual features maintaining the greatest prognostic significance for event-free survival (EFS, the main endpoint of the IELSG-19 trial) were age ≥70 years (HR 1.72, 95% CI 1.26-2.33), Ann Arbor stage III or IV (HR 1.79, 95% CI 1.35-2.38), and elevated LDH level (HR 1.87, 95% CI 1.27-2.77). The prognostic index (MALT-IPI) constructed using these three parameters identified three groups: low, intermediate and high risk (corresponding to the presence of 0, 1 or ≥2 of these factors, respectively). The 5-year EFS rates in the low, intermediate and high risk groups were 70%, 56% and 29%, respectively. The MALT-IPI also significantly discriminated between patients with different progression-free, overall and cause-specific survival. The prognostic utility was retained in gastric and non-gastric lymphomas, in each treatment arm (chlorambucil, rituximab, rituximab plus chlorambucil), and was confirmed in the validation set. The new index, MALT-IPI, is a simple, accessible and effective tool to identify MALT lymphoma patients at risk of poor outcomes. It may help define appropriate treatment approaches for individual patients.