Introduction
The majority of patients with thyroid carcinoma have well-differentiated disease limited to the thyroid gland. However, 6–13% of these tumors can present with extra-thyroid extension (ETE). [1, 2] ETE has been well-recognized as a poor prognostic indicator, with 10-year overall survival (OS) rates dropping by more than 50% compared to tumors without ETE [3].
Tracheal invasion is a specific form of ETE and it is often recognized only at the time of surgery.[4] Surgical techniques for treating tracheal invasion range from shaving the trachea to various forms of tracheal resection. Tracheal shaving is commonly performed for tumors with minimal invasion of the perichondrium, and it consists of sharp removal of all gross disease from the surface of the trachea while leaving the mucosa intact.[4, 5] Shave excision harbors a high risk of microscopic residual disease,[6-8] A number of studies reported similar survival and local control rates for shave resections and more aggressive procedures in carefully selected patients.[9-11] That finding, however, has been called into question by the demonstration of a worse survival and a higher recurrence rate in shave resections, despite adjuvant radioactive iodine (RAI) and external beam radiotherapy.[12, 13]
The aim of this study was to compare outcomes of minimal tracheal invasion to other forms of ETE, and to analyze outcomes according to the eighth edition of the American Joint Committee on Cancer (AJCC) staging manual.