Event-free survival at 36 months is a suitable endpoint for diffuse large B-cell lymphoma patients treated with immunochemotherapy: real-world evidence from the North Japan Hematology Study Group

Abstract

Information regarding follow-up duration after treatment for newly diagnosed diffuse large B-cell lymphoma (DLBCL) is important. However, a clear endpoint has yet to be established. We totally enrolled 2182 patients newly diagnosed with DLBCL between 2008 and 2018. The median age of the patients was 71 years. All patients were treated with rituximab- and anthracycline-based chemotherapies. Each overall survival (OS) was compared with the age- and sex-matched Japanese general population (GP) data. At a median follow-up of 3.4 years, 985 patients experienced an event and 657 patients died. Patients who achieved an event-free survival (EFS) at 36 months (EFS36) had an OS equivalent to that of the matched GP (standard mortality ratio [SMR], 1.17; P=0.1324), whereas those who achieved an EFS24 did not have an OS comparable to that of the matched GP (SMR, 1.26; P=0.0095). Subgroup analysis revealed that relatively old patients (>60 years), male patients, those with limited-stage disease, those with a good performance status, and those with low levels of soluble interleukin 2 receptor already had a comparable life expectancy to the matched GP at an EFS24. In contrast, relatively young patients had a shorter life expectancy than matched GP, even with an EFS36. In conclusion, an EFS36 was shown to be a more suitable endpoint for newly diagnosed DLBCL patients than an EFS24. Of note, younger patients require a longer EFS period than older patients in order to obtain an equivalent life expectancy to the matched GP.