Prognostic factors of locally invasive well-differentiated thyroid carcinoma involving the trachea.

To report our experience with tracheal invasive thyroid carcinoma with emphasis on clinical characteristics and treatment modalities, and to identify the prognostic factors for tracheal invasive thyroid carcinoma. Totally 1919 patients underwent surgical extirpation of thyroid cancer from 1990 to 2010. Among them, 65 patients had well-differentiated thyroid cancer with tracheal invasion. The incidence was higher in male and older patients. Patients were treated with tracheal shave excision (n = 18), tracheal resection (n = 37) and total laryngectomy (n = 10). Locoregional recurrence occurred in 39 patients, and metastasis occurred in 25 patients. Simultaneous involvement of the trachea and the esophagus was associated with locoregional recurrence (p = 0.039) in univariate analysis, but not confirmed by multivariate analysis. There was significant difference in the disease-specific survival (DSS) according to laryngeal involvement (p = 0.002). All the patient in the shave excision group survived until the end of the study period. Although it is categorized in same classification of T4a, simultaneous involvement of the trachea and the esophagus showed higher locoregional recurrence and laryngeal involvement showed lower DSS. Despite the invasion of thyroid cancer into the adjacent aerodigestive tract, many patients showed long survival when they underwent appropriate surgery.