Blood-Based Inflammatory and Metabolic Biomarkers for Assessing Symptom Burden and Quality of Life in Older Adults with Cancer: A Narrative Review

BACKGROUND: To evaluate the clinical utility of blood-based inflammatory and metabolic biomarkers in assessing symptom burden and quality of life among older adults with cancer. METHODS: This review synthesizes current evidence regarding the clinical utility and underlying pathophysiological mechanisms of blood-based biomarkers, focusing particularly on the neutrophil-to-lymphocyte ratio (NLR), systemic immune-inflammation index (SII), and modified Glasgow prognostic score (mGPS). RESULTS: Elevated inflammatory markers, such as NLR and SII, independently correlate with increased frailty and functional decline. Concurrently, nutritional-metabolic markers, including hypoalbuminemia and a high mGPS, are strongly associated with anorexia and cancer cachexia. These composite indicators effectively capture the synergistic effects of "inflammaging", neuroinflammation, and tumor-driven metabolic reprogramming. CONCLUSION: Objective, cost-effective, and dynamically measurable inflammatory and metabolic biomarkers represent promising adjunctive tools for early symptom screening. The integration of these markers into comprehensive geriatric assessments may enhance risk stratification and symptom management. However, current evidence is constrained by study heterogeneity, retrospective designs, a lack of standardized cutoffs, and insufficient prospective validation in older cancer populations. Therefore, these biomarkers should be regarded as complementary to traditional assessments rather than definitive standalone tools.