Local prognosis of patients with papillary thyroid carcinoma who were intra-operatively diagnosed as having minimal invasion of the trachea: a 17-year experience in a single institute.

Background: Since papillary thyroid carcinoma (PTC) with tracheal invasion shows a worse prognosis, aggressive surgical treatment including airway resection has been recommended. However, little is known about local recurrence of PTC with minimal tracheal invasion after shaving or laminated resection of the tracheal cartilage. In this study, we investigated the local prognosis of patients who were intra-operatively diagnosed as having minimal tracheal invasion.

Methods: Of 6,015 patients who underwent initial surgery for PTC between 1987 and 2004, 127 (2.1%) were intra-operatively suspected of having minimal invasion to the trachea and underwent shaving or laminated resection of the tracheal cartilage. These 127 patients were enrolled in this study.

Results: Of 127 patients, 107 were intra-operatively regarded as having received macroscopically curative treatment (curative group), whereas minimal carcinoma remnants were suspected in the remaining 20 patients (suspicious group). To date, six patients (4.6%) (one patient in the curative group and five in the suspicious group) showed local recurrence at the tracheal edge. The local disease-free survival of patients in the curative group was better than that of those in the suspicious group (p = 0.0007), although the cause-specific survival of patients in the two groups did not differ. Cut surfaces of resected carcinoma were also pathologically examined for 119 patients and 58 (48.7%) were diagnosed as carcinoma-positive, but the cut surface status was not related to macroscopic curative treatment. Of six patients showing local recurrence, only one died of lung metastasis of carcinoma.

Conclusion: The incidence of local recurrence of PTC with minimal tracheal invasion is low at 4.6%. Although this event might not be immediately life-threatening for patients, to improve local prognosis, local curative treatment should be pursued. In cases that are suspected of persistent carcinoma remnants, further shaving or laminated dissection should be performed, and if the carcinoma remnant cannot be eliminated, tracheal fenestration should be considered, although such high-risk tumours may be likely to recur regardless of surgical radicality.