LDHA and head and neck squamous cell carcinoma: Importantly, external validation in an independent real-world SAZHU-HNSCC cohort confirmed that model-predicted LAC_H tumors exhibited significantly increased protein expression of LDHA and MCT1 by immunohistochemistry, supporting the biological validity of the digital lactate biomarker.<h4>Conclusions</h4>This study integrates multi-omics and digital pathology to infer tumor lactate metabolism from routine histology, providing a scalable and clinically practical digital biomarker for metabolism-informed precision oncology.