Discovery and Validation of Lung Cancer Biomarkers Based on Proteomic Analysis of Bronchoalveolar Lavage Fluid from the Self-Controlled Pulmonary Lobes

< 0.05; |FC| > 1.2). Pathway analysis revealed significant enrichment of these dysregulated proteins in metabolic pathways and the TCA cycle. Subsequent validation in an independent cohort confirmed that two candidate proteins, SUCLA2 and FKBP9, were significantly upregulated specifically in cancerous lobes. To our knowledge, this is the first report identifying SUCLA2 and FKBP9 as lung cancer-specific biomarkers detectable in BALF using a self-controlled study design. These findings provide crucial insights into the metabolic reprogramming of early stage lung cancer and offer promising novel targets for improving the differential diagnosis of indeterminate pulmonary nodules.