P4HA1 and head and neck squamous cell carcinoma: The AUC value of TCGA and validation cohort was 0.887 and 0.883, respectively, signifying greater diagnostic accuracy compared with conventional cancer‐related biomarkers, such as carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC Ag), TPS (tissue polypeptide specific antigen), and Cyfra 21‐1.31, 32 These results suggest that P4HA1 expression levels might represent a promising diagnostic biomarker for HNSCC.