Comparing the Therapeutic Efficacy of Extended Isthmusectomy Versus Total Thyroidectomy for Isthmus Tumors of the Thyroid

Inclusion Criteria: \- Age 18 years or older. Diagnosis of low-risk differentiated thyroid cancer (papillary, follicular, or Hürthle cell carcinoma). Unifocal tumor located in the thyroid isthmus, cT1b No evidence of extrathyroidal extension, assessed by preoperative ultrasound. Exclusion Criteria: \- Aggressive pathological subtypes (e.g., tall cell, clear cell, columnar cell, or diffuse sclerosing variants of papillary thyroid carcinoma, as well as poorly differentiated types). cN1b. M1 Combined with other suspicious thyroid nodules within the lobes.