Surgery for Thyroid Cancer Invading the Trachea.

Thyroid cancer invading the trachea can be asymptomatic, but when tumour invasion reaches the mucosal surface, it causes bloody sputum and dyspnoea. The treatment plan for thyroid cancer is determined based on the site, depth, and extent of the invasion. Different from tumours arising from the tracheal mucosa, in thyroid cancer, invasion begins outside the airway and progresses toward the lumen, making it difficult to accurately diagnose the extent of the invasion even with bronchoscopy. Therefore, surgeons must determine the range of resection during surgery. Invasion reaching the tracheal mucosa requires full-thickness resection and is performed using tracheal window resection combined with tracheocutaneous fistula or tracheal sleeve resection followed by end-to-end anastomosis. The airway is safely secured with window resection, but closing the tracheal stoma often requires multi-stage reconstruction. Sleeve resection is an oncologically appropriate surgical method that can be completed in one stage, although there is a risk of serious complications associated with anastomotic dehiscence. Since well-differentiated thyroid cancer progresses slowly, some degree of survival can be expected even with incomplete resection. However, when shaving is performed for tumours with deep invasion that reaches the tracheal mucosa, the residual tumour tissue continues to grow steadily and eventually leads to airway stenosis. Since reoperation for tracheal resection is difficult, radical full-thickness resection should be performed in the initial surgery. Although this surgical intervention is far more demanding for both patients and surgeons than shaving, the procedure eventually improves patient's prognosis and quality of life.