TG and medullary thyroid gland carcinoma: Patients with lower preoperative thyroglobulin levels (<30 ng/mL) had significantly better five-year survival rates (82.1% for PTC and 78.5% for medullary thyroid carcinoma [MTC]) compared to those with higher levels (≥30 ng/mL), where survival rates dropped to 67.5% and 60.4%, respectively.