Association Between Red Blood Cell Distribution Width‐To‐Albumin Ratio and Breast, Colorectal, Lung, and Prostate Cancers

INTRODUCTION: Cancer remains a leading cause of global morbidity and mortality, underscoring the need for accessible biomarkers for early detection and risk stratification. The red blood cell distribution width-to-albumin ratio (RAR) integrates inflammation and nutritional markers often dysregulated in cancer. We evaluated RAR's association with a recent diagnosis (≤ 1 year) of breast, colorectal, lung, and prostate cancer in a representative US population. METHODS: Using National Health and Nutrition Examination Survey data (2005-2018), we conducted a cross-sectional analysis of adults with recent diagnoses (≤ 1 year) of a single primary cancer. Propensity score matching balanced cases and cancer-free comparisons by age, sex, and race. Weighted logistic regression assessed associations between a 1-unit RAR (%dL/g) increase and cancer presence, reporting adjusted odds ratios (ORs) with 95% confidence intervals (CIs). RESULTS: The analysis included 48 breast, 31 colorectal, 19 lung, and 77 prostate cancer cases, along with their matched comparisons. A 1% dL/g increase in RAR was significantly associated with higher odds of breast (adjusted OR 1.62, 95% CI 1.17-2.24), colorectal (adjusted OR 1.56, 95% CI 1.01-2.40), and lung cancer (adjusted OR 1.95, 95% CI 1.44-2.66). No significant association was observed for prostate cancer (adjusted OR 1.05, 95% CI 0.69-1.59). CONCLUSION: RAR is significantly associated with a recent diagnosis of breast, colorectal, and lung cancers, but not prostate cancer. These findings suggest RAR may reflect cancer-associated systemic alterations, warranting further prospective study to validate its clinical applicability.