CLINICAL ANALYSIS OF 670 CASES IN 2 TRIALS OF THE EUROPEAN ORGANIZATION FOR THE RESEARCH AND TREATMENT OF CANCER LYMPHOMA COOPERATIVE GROUPSUBTYPED ACCORDING TO THE REVISED EUROPEAN-AMERICAN CLASSIFICATION OFLYMPHOID NEOPLASMS - A COMPARISON WITH THE WORKING FORMULATION

In the Working Formulation (WF), non-Hodgkin's lymphomas (NHL) are gro uped according to their clinical behavior. These disorders are listed as entities defined by morphology, phenotype, and cytogenetics in the proposed Revised European-American Classification of Lymphoid Neoplasm s (REAL), the clinical relevance of which is still debated. We analyze d 670 NHL cases included in two randomized clinical trials (EORTC 2085 5 WF-intermediate/high-grade and 20856 WF-low-grade malignancy) with h istologic material available for review. Based on hematoxylin-eosin-st ained sections, 77% of cases could be subtyped. Immunophenotyping was considered to be mandatory only in diagnosing T-cell lymphoma and anap lastic large-cell lymphoma. Of 522 cases subtyped, 11% were mantle cel l lymphoma (MCL), 5% were marginal zone B-cell lymphoma (MZBCL), 46% w ere follicle center lymphoma, and 32% were diffuse large B-cell lympho ma. Statistical analysis and comparisons between classifications were made only within each trial and treatment group. MCL and MZBCL were ch aracterized by a shorter median survival (3.4 and 4.1 years, respectiv ely) in comparison with low- and intermediate-grade WF groups (>9.3 an d 5.8 years, respectively). In terms of progression-free survival, MCL showed a behavior similar to the low-grade group, with frequent relap ses. Follicle center cell lymphomas behaved as low-grade lymphomas as defined by the WF and diffuse large B-cell lymphomas as the WF-interme diate grade group. Because several NHL entities have a clinical behavi or of their own, their recognition by the REAL classification offers c linicians additional information that is not obtained when the WF is u sed. (C) 1996 by The American Society of Hematology.