Association of baseline vitamin D levels with survival and disease control in diffuse large B-cell lymphoma: A meta-analysis.

e19082 Background: Vitamin D enhances antibody-dependent cellular cytotoxicity, a key mechanism underlying anti-CD20 monoclonal antibody activity in diffuse large B-cell lymphoma (DLBCL). Prior studies suggest that baseline vitamin D deficiency may be associated with inferior outcomes, but the magnitude and consistency of this association remain incompletely defined. We performed a systematic review and meta-analysis to quantify the prognostic impact of baseline vitamin D deficiency on survival and disease control outcomes in DLBCL and related large B-cell lymphomas. Methods: PubMed, Embase, and Web of Science were searched through 2025 for studies reporting associations between baseline serum 25-hydroxyvitamin D levels and outcomes in DLBCL or large B-cell lymphoma. Eligible studies reported hazard ratios (HRs) for overall survival (OS), event-free survival (EFS), progression-free survival (PFS), or lymphoma-specific survival (LSS), comparing low versus higher vitamin D levels. Random-effects meta-analyses were performed using the generic inverse-variance method. Heterogeneity was assessed using the I² statistic. Results: Eleven studies comprising 2,218 patients were included. Baseline vitamin D deficiency was significantly associated with inferior disease control (EFS, PFS, and LSS), with a pooled HR of 1.97 (95% CI: 1.57–2.47; p < 0.0001) and moderate heterogeneity (I² = 41.6%). In the analysis of overall survival across nine studies, vitamin D deficiency was strongly associated with worse OS, with a pooled HR of 2.33 (95% CI: 1.89–2.87; p < 0.0001). Heterogeneity for OS was negligible (I² = 0%), indicating highly consistent effects across cohorts. The adverse prognostic association was most pronounced in patients treated with rituximab-containing immunochemotherapy. Conclusions: Baseline vitamin D deficiency is associated with significantly inferior overall survival and disease control in DLBCL and related large B-cell lymphomas, with approximately a two-fold increased risk of death and progression or relapse. These findings support baseline vitamin D status as a readily measurable prognostic biomarker and provide strong rationale for prospective interventional trials to determine whether correction of vitamin D deficiency can improve outcomes.