Impact of event-free survival status after stem cell transplantation on subsequent survival of patients with lymphoma

We evaluated the impact of event-free survival (EFS) status at 24 months (EFS24) and 60 months (EFS60) after hematopoietic stem cell transplantation (HSCT) using registry data. Patients who underwent their first autologous HSCT (auto-HSCT) or allogeneic HSCT (allo-HSCT) for lymphoma between 1981 and 2018 were included. Overall survival was compared with that of the age-, sex, and calendar period-matched general population. A total of 14 977 patients, including 10 964 and 4013 who underwent auto-HSCT and allo-HSCT, respectively, were analyzed. Although patients who achieved EFS24 and EFS60 had favorable outcomes, most had significantly poorer survival rates than the general population. The standardized mortality ratios (SMRs) of patients with diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) were significantly higher than that of the general population even after achieving EFS24 or EFS60. The SMRs of those after auto-HSCT were 2.5 to 3.5 and 2.7 to 3.7, respectively. The SMR was consistently highest in Hodgkin lymphoma (HL) patients after HSCT. By contrast, subsequent survival of patients with primary mediastinal large B-cell lymphoma, intravascular large B-cell lymphoma, or peripheral T-cell lymphoma, not otherwise specified, who achieved EFS60 after auto-HSCT, and those with extranodal natural killer/T-cell lymphoma who achieved EFS60 after allo-HSCT did not significantly differ from that of the general population, with SMRs of 1.6, 1.2, 1.8, and 1.3, respectively. Our results suggest that EFS24 and EFS60 were clinically useful end points after HSCT for lymphoma patients. Furthermore, patients with certain lymphoma subtypes who achieved EFS had a comparable prognosis with that of the general population and were potentially cured after HSCT.