Prognostic Impact of Prephase Treatment Prior to First-Line Treatment in DLBCL: A Population-Based Registry Study

Introduction. Prephase treatment (PP) is recommended in diffuse large B-cell lymphomas (DLBCL) to decrease therapy-related toxicities and to avoid tumour lysis syndrome. Data in the real world are limited, and no study has evaluated the impact on overall survival. We aimed to evaluate overall survival (OS), progression-free survival (PFS), and grade III-IV toxicities during the first cycle according to PP. Methods and Materials. All DLBCL diagnosed between 2014 and 2017 and aged between 18 and 80 years were identified by the Poitou-Charentes General Cancer Registry (France). PP was defined as any treatment prior to first-line, excluding anthracycline and/or Rituximab. We performed propensity score matching (PSM) to control characteristics at diagnosis, reduce bias, and approximate a randomized trial. Results. Three hundred and forty patients received first-line treatment in 17 hospital centers: 126 (37%) with prephase and 214 (63%) without prephase (NPP). After PSM, 97 patients remained in each group without significant difference in characteristics at diagnosis; matched PP patients had a 2-year OS of 71% (vs. 77%, $P$ = 0.32), a 2-year PFS of 61% (vs. 74%, $P$ = 0.12), and 26% grade III-IV toxicities (vs. 27%, $P$ = 0.75). No tumour lysis syndrome was reported. PP nonsignificantly decreases grade III-IV toxicities for patients with high tumour load ( $P$ = 0.82) or elderly patients ( $P$ = 0.81). Conclusion. PP treatment does not affect survival nor does it reduce therapy-related toxicities even for patients with high tumour load or elderly patients. Further studies are needed to evaluate the efficacy and safety of PP.