Clinical Impact of the Geriatric Nutritional Risk Index on Chemotherapy-Related Adverse Events in Diffuse Large B-Cell Lymphoma: A Multicenter Study

<b>Background/Objectives:</b> Accurate prediction of severe adverse events (SAEs) is crucial for optimizing supportive care while maintaining treatment intensity in diffuse large B-cell lymphoma (DLBCL). We evaluated the predictive value of the Geriatric Nutritional Risk Index (GNRI) for SAEs in de novo DLBCL and examined potential interactions with treatment regimen and age. <b>Methods:</b> This multicenter retrospective study included 555 adults treated with standard immunochemotherapies. SAEs, defined as grade ≥ 3 non-hematological adverse events or febrile neutropenia, were independently assessed by board-certified hematologists. <b>Results:</b> Multivariable logistic regression identified GNRI as an independent predictor of SAEs (odds ratio 0.982, 95% confidence interval 0.967-0.997). Restricted cubic spline modeling revealed a significant non-linear association between GNRI and SAE risk (<i>p</i> = 0.045). No significant interaction was observed between GNRI and regimen or age (<i>p</i> = 0.894 and 0.217, respectively), a finding consistent across subgroups in forest plot analyses. <b>Conclusions:</b> This study showed that lower diagnostic GNRI was independently associated with higher SAE risk regardless of treatment regimen or age. These findings highlight the potential utility of GNRI as a simple clinical indicator for identifying patients at higher risk of treatment-related toxicity, although they are derived from a retrospective, tertiary-care cohort and require confirmation in external prospective studies.