Minimal Extrathyroidal Extension in Bilateral Papillary Thyroid Carcinoma Is Associated With Postoperative Structural...

Area of Science:

• Endocrinology
• Oncology
• Surgical Pathology

Background:

• The American Joint Committee on Cancer (AJCC) staging system no longer includes minimal extrathyroidal extension (mETE) in the T3 category for thyroid cancer.
• Despite exclusion from T3 staging, mETE remains an intermediate-risk feature associated with recurrence in thyroid cancer.
• The prognostic value of mETE and its impact on recurrence risk are debated.

Purpose of the Study:

• To evaluate the prognostic significance of minimal extrathyroidal extension (mETE) in papillary thyroid carcinoma (PTC).
• To determine the association between mETE and structural recurrence risk in PTC patients.

Main Methods:

• Retrospective analysis of 1870 papillary thyroid carcinoma (PTC) patients.
• Patients underwent total thyroidectomy (TT) with central lymph node dissection (CLND) between 2015 and 2020.
• Cox proportional hazards regression and subgroup analyses were used to assess mETE's association with structural recurrence.

Main Results:

• A total of 124 patients (6.6%) experienced structural recurrence after a median follow-up of 27.9 months.
• Patients with mETE had a significantly higher recurrence rate (11.0%) compared to those without (5.6%).
• mETE was an independent risk factor for recurrence, particularly in patients with bilateral tumors and without Hashimoto's thyroiditis (HT). A significant interaction between tumor bilaterality and mETE was observed.

Conclusions:

• Minimal extrathyroidal extension (mETE) is a significant prognostic factor for structural recurrence in PTC, associated with decreased disease-free survival (DFS).
• mETE elevates recurrence risk in bilateral PTC to near the ATA intermediate-high threshold, irrespective of tumor size.
• The synergy between mETE and tumor bilaterality warrants consideration for upgraded risk stratification and intensified surveillance in affected patients.