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

The thyroid isthmus is a narrow structure connecting the two lobes of the thyroid. Papillary carcinoma arising from this site accounts for only 1-9% of all thyroid cancers. However, due to its unique anatomical location, it is more prone to extranodal extension and bilateral lymph node metastasis, exhibiting more aggressive biological behavior. The optimal extent of surgery remains controversial: total thyroidectomy facilitates postoperative radioactive iodine therapy and monitoring but results in permanent dependence on thyroid hormone replacement and increases the risk of complications such as hypocalcemia, adversely affecting patients' quality of life. In contrast, conservative approaches like extended isthmusectomy can preserve partial thyroid function, reduce complications, and maintain a better quality of life, making them particularly suitable for low-risk patients with small tumors and no metastasis. Existing retrospective studies indicate no significant difference in recurrence rates between the two surgical approaches, though the evidence remains limited. Therefore, this study aims to conduct a prospective, multicenter, open-label, parallel-controlled, randomized trial to directly compare total thyroidectomy and extended isthmusectomy in terms of postoperative recurrence rates, quality of life, and complications, thereby providing high-quality evidence for surgical decision-making.

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.