Obesity as a Risk Factor and Prognostic Indicator for B-cell Lymphoma: An Umbrella Review

Introduction: Obesity constitutes an important risk factor for numerous chronic diseases, including various types of cancer. Epidemiological evidence shows that individuals with elevated body mass index (BMI) present a higher incidence of malignant tumors, including hematological neoplasms like B-cell lymphomas. Objective: To synthesize and evaluate the available evidence regarding the dual role of obesity both as a risk factor for developing B-cell lymphoma and as a prognostic indicator in patients already diagnosed with this malignancy. Methodology: This umbrella review followed PRISMA guidelines. A comprehensive search was conducted in PubMed/MEDLINE, Scopus, Embase, Web of Science, and Cochrane databases. Studies were included if they were systematic reviews or meta-analyses examining obesity/BMI as a risk factor or prognostic indicator for B-cell lymphoma, particularly DLBCL. The ROBIS tool was used to assess methodological quality. Results: Systematic reviews consistently demonstrate that elevated BMI increases the risk of developing DLBCL, with relative risk estimates between 1.11-1.31. Obese individuals have approximately 11-31% greater risk compared to those of normal weight, with stronger associations observed for BMI during early adulthood. For prognosis, while underweight consistently shows negative effects on survival, the impact of overweight and obesity varies. One review identified a protective effect of overweight (BMI 25-29.9 kg/m²) on overall survival (HR=0.86), suggesting an "obesity paradox," while others found neutral effects. Conclusions: The obesity-lymphoma relationship involves chronic inflammation, adipokine dysregulation, insulin resistance, and altered tumor microenvironment. Clinical recommendations include detailed body composition assessments, personalized nutritional interventions, and adapted physical exercise programs.