Expression analysis using RT-qPCR revealed significant (p-value < 0.05) down-regulation of BRAF, EIF1 AX, FOXE1, KRAS, PDGFRA, PIK3 CA, PTEN, and TERT genes in thyroid cancer cell lines compared to controls, with ROC curves indicating high diagnostic accuracy (AUC 0.93–0.99). This evidence concerns the gene PIK3CG and thyroid gland carcinoma.