(A568) Isthmusectomy for papillary thyroid cancer: a single center experience

Introduction: Papillary thyroid carcinoma (PTC) is the most common thyroid cancer, representing 85% of differentiated thyroid cancers, and the current guidelines recommend thyroid lobectomy or total thyroidectomy as primary surgical management. However, these surgeries may represent overtreatment for tumors confined to the isthmus, leading to unnecessary post-operative morbidity. We aim to report our experience with isthmusectomy for PTCs, evaluating disease outcomes and postoperative complications.

Methods: We completed a retrospective chart review of 4611 patients treated for PTC with primary surgery at our institution between 1999 and 2024, of which 21 underwent an isthmusectomy. Patient demographics, surgical extent, and tumor histopathologic characteristics were collected. Disease free survival was also evaluated.

Results: 21 patients (median age 44 years; range: 32-67), mostly female (20/21) and white (12/21) were included. One had prior radiation exposure to the head and neck. Pre-operatively on ultrasound, median tumor size was 1.2 cm (range: 0.7-2.7 cm), and there was no extrathyroidal extension or central lymph node involvement. All patients underwent an isthmusectomy, while one also had a central neck dissection. 13/21 had central neck lymph node sampling at the time of surgery. Overall, 7/14 patients with nodal excision had positive disease. None of the patients reported postoperative complications such as hypothyroidism, hypoparathyroidism, or recurrent laryngeal nerve injury. Histopathologically, the median tumor size was 1 cm (range: 0.3-2.1cm). Two (10%) patients had multifocal disease, none had gross extrathyroidal extension, while 7 (33%) had microscopic extrathyroidal extension into the perithyroidal soft tissue. In addition, 3 (14%) tumors had lymphovascular invasion. The disease specific survival was 100% with a median follow up of 4.2 years (range: 0.1-10.7 years).

Conclusions: Isthmusectomy for PTC confined to the isthmus is a viable surgical option for select patients and offers favorable outcomes and minimal postoperative complications.