Omission of Radiotherapy in Primary Mediastinal B-Cell Lymphoma: IELSG37 Trial Results
Maurizio Martelli, Luca Ceriani, Giovannino Ciccone, Umberto Ricardi, Iryna Kriachok, Barbara Botto, Monica Balzarotti, Alessandra Tucci, Sara Veronica Usai, Vittorio Ruggero Zilioli, Elsa Pennese, Luca Arcaini, Anna Dąbrowska‐Iwanicka, Andrés J.M. Ferreri, Francesco Merli, Weili Zhao, Luigi Rigacci, Claudia Cellini, David Hodgson, C Ionescu, Carla Minoia, Elisa Lucchini, Michele Spina, Alexander Fosså, Andrea Janíková, Kate Cwynarski, N. George Mikhaeel, Mats Jerkeman, Alice Di Rocco, Yana Stepanishyna, Umberto Vitolo, Armando Santoro, Alessandro Re, Benedetta Puccini, Jacopo Olivieri, Luigi Petrucci, Sally F. Barrington, Bogdan Małkowski, Ur Metser, Annibale Versari, Stéphane Chauvie, Jan Walewski, Marek Trněný, F. Cavalli, Mary Gospodarowicz, Peter Johnson, Andrew Davies, Emanuele Zucca, on behalf of the International Extranodal Lymphoma Study Group (IELSG), Mary Gospodarowicz, David Hodgson, John Kuruvilla, Li Wang, Weili Zhao, David Balada, Andreas Huettmann, F. Angrilli, Ombretta Annibali, Luca Arcaini, Oreste Bagni, Monica Balzarotti, Roberta Battistini, Barbara Botto, Maria Giuseppina Cabras, Teresa Calimeri, Califano Catello, Federica Cavallo, Claudia Cellini, Patrizia Ciammella, Ugo Consoli, Vitaliana De Sanctis, Nicola Di Renzo, Alice Di Rocco, Alberto Fabbri, Angela Ferrari, Andrés J.M. Ferreri, Leonardo Flenghi, Gianluca Gaïdano, Guido Gini, Manuel Gotti, Attilio Guarini, Anna Marina Liberati, Elisa Lucchini, Donato Mannina, Maurizio Martelli, Fabio Matrone, Francesco Merli, Carla Minoia, Anna Lia Molinari, Gerardo Musuraca, Luca Nassi, Jacopo Olivieri, Francesco Passamonti, Domenico Pastore, Caterina Patti, Sabrina Pelliccia, Elsa Pennese, Luigi Petrucci, Francesco Piazza, Francesco Pisani
Abstract
PURPOSE: The role of consolidation radiotherapy in patients with primary mediastinal B-cell lymphoma (PMBCL) is controversial. METHODS: The IELSG37 trial, a randomized noninferiority study, aimed to assess whether irradiation can be omitted in patients with PMBCL with complete metabolic response (CMR) after induction immunochemotherapy. The primary end point was progression-free survival (PFS) at 30 months after random assignment. Patients with CMR were randomly assigned to observation or consolidation radiotherapy (30 Gy). With a noninferiority margin of 10% (assuming a 30-month PFS of 85% in both arms), a sample size of 540 patients was planned with 376 expected to be randomly assigned. RESULTS: The observed events were considerably lower than expected; therefore, primary end point analysis was conducted when ≥95% of patients were followed for ≥30 months. Of the 545 patients enrolled, 268 were in CMR after induction and were randomly assigned to observation (n = 132) or radiotherapy (n = 136). The 30-month PFS was 96.2% in the observation arm and 98.5% in the radiotherapy arm, with a stratified hazard ratio of 1.47 (95% CI, 0.34 to 6.28) and absolute risk difference of 0.68% (95% CI, -0.97 to 7.46). The 5-year overall survival (OS) was 99% in both arms. Nonrandomized patients were managed according to local policies. Radiotherapy was the only treatment in 86% of those with Deauville score (DS) 4 and in 57% of those with DS 5. The 5-year PFS and OS of patients with DS 4 (95.8% and 97.5%, respectively) were not significantly different from those of randomly assigned patients. Patients with DS5 had significantly poorer 5-year PFS and OS (60.3% and 74.6%, respectively). CONCLUSION: This study, the largest randomized trial of radiotherapy in PMBCL, demonstrated favorable outcomes in patients achieving CMR with no survival impairment for those omitting irradiation.