[Clinical issues and perspectives in diffuse large B-cell lymphoma based on 15 years of clinical studies by the Kyoto Hematology Clinical Research Group (KOTOSG)].

Since 2010, the Kyoto Hematology Clinical Research Group (KOTOSG), a multicenter clinical research group, has dedicated itself to clinical studies on hematological diseases based on daily clinical practice. These studies have provided information about patient characteristics, treatment outcomes, and adverse events in actual clinical practice, and have improved the standard of local medical care by uncovering differences between facilities. In addition, study results have clarified ongoing problems that pose the next challenges for both clinical and basic research. The disease most widely studied was diffuse large B-cell lymphoma (DLBCL). Studies related to DLBCL covered various topics: (1) development of a new prognostic index that can identify highly refractory patients with high accuracy, such as the Kyoto Prognostic Index (KPI) for newly diagnosed DLBCL and KPI-R for relapsed/refractory DLBCL, (2) identification of cytogenetic and clinicopathological characteristics of patients with a poor prognosis, and (3) issues with second cancers after successful treatment. In this article, we review the results of clinical studies on DLBCL by KOTOSG, comparing them with those of past clinical studies in DLBCL, mainly those conducted in Japan. We hope these studies will help to advance the field of clinical hematology.