Prognostic Value of the CALLY Index in Diffuse Large B-Cell Lymphoma: Linking Inflammation, Nutrition, and Tumor Biology

Background/Objectives: Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma and remains incurable in approximately 30–40% of patients despite advances in immunochemotherapy. Although gene expression profiling has improved risk stratification, there is an ongoing need for non-invasive, cost-effective, and clinically practical biomarkers to identify patients at high risk of treatment resistance or relapse (R/R). Systemic inflammation plays a pivotal role in DLBCL pathogenesis, impacting both tumor progression and treatment response. The C-reactive protein–albumin–lymphocyte (CALLY) index, integrating markers of inflammation, nutritional status, and immune competence, has demonstrated prognostic relevance in solid tumors; however, its relevance in hematologic malignancies remains unexplored. Methods: We retrospectively analyzed 180 adults with newly diagnosed DLBCL, NOS (not otherwise specified) who received frontline rituximab-based immunochemotherapy (R-CHOP or CHOP-like regimens) between January 2014 and December 2019 at three tertiary centers in Serbia. The median age was 67 years (IQR 59–73), and 56.1% were female. Receiver operating characteristic (ROC) analysis determined 6.5 as the optimal CALLY index cut-off (AUC 0.744, 95% CI 0.670–0.817; p < 0.001). Results: A low CALLY index (