Association of inflammation-related composite indices with lung cancer risk in US adults and all-cause mortality among lung cancer patients: evidence from the 1999–2018 NHANES

BACKGROUND: Chronic inflammation is implicated in lung cancer pathogenesis. Inflammation-related haematologic indices are accessible biomarkers, but their associations with lung cancer risk and mortality in the general US population are not well-established. AIM: To investigate the associations of five inflammation-related haematologic indices (NLR, MLR, NMLR, ALI, PIV) with lung cancer risk and all-cause mortality among US adults. SUBJECTS AND METHODS: This population-based study analysed 47,862 adults from the 1999-2018 NHANES. Lung cancer was self-reported. Associations with lung cancer risk in the overall study population and with all-cause mortality among participants with lung cancer (followed through 2019) were assessed using weighted logistic and Cox regression models, respectively. Sensitivity analyses, including machine learning, were performed. RESULTS: Among participants, 114 had lung cancer. Higher NLR, MLR, NMLR, and PIV were significantly associated with increased lung cancer risk (e.g. per 1-SD increase: MLR OR = 1.50) and all-cause mortality (e.g. MLR HR = 1.40). Conversely, higher ALI was associated with decreased risk (OR = 0.58) and mortality (HR = 0.53). MLR showed the highest discriminative ability for risk (AUC = 0.715). Sensitivity analyses confirmed robustness. CONCLUSION: Inflammation-related haematologic indices are significantly associated with lung cancer risk and prognosis. These low-cost biomarkers show potential for risk stratification and prognostic assessment.