HTRA1 and head and neck squamous cell carcinoma: To further validate the performance of HtrAs, an ROC curve was plotted, and the area under the curve (AUC) of HtrA1-4 genes were 0.828, 0.901, 0.833, and 0.829, respectively (Fig. 4E), indicating that HtrAs could be potential diagnostic markers for HNSCC.