Clinical epidemiology of tracheal invasion from thyroid cancer in Japanese population: Functional outcomes and effect of aging

Background Although tracheal invasion from thyroid cancer is life-threatening, the epidemiology of its development remains unclear. This study aimed to determine the epidemiology (prevalence, incidence, and risk factors) and functional outcomes of tracheal invasion from thyroid cancer among Japanese patients who were eligible for full-layer tracheal resection. Methods Patients with thyroid cancer and with or without tracheal invasion were identified based on procedure codes using a large inpatient database that is maintained by a data vendor. The prevalence and incidence were estimated for each age and sex using Japanese volume of thyroidectomies and Japanese population data. We also explored whether a tumor-related tracheal defect was successfully reconstructed after full-layer tracheal resection. Results Among the 8482 patients with thyroid cancer, the overall prevalence of tracheal invasion was 0.4–0.7%. The overall incidence of thyroid cancer was 12.0/100,000 persons, and the incidence of tracheal invasion was estimated to be 0.05–0.09/100,000 persons. The age distributions were noticeably different between thyroid cancer cases with and without tracheal invasion. The highest incidence was observed at ages of 70–79 years for thyroid cancer with tracheal invasion and 60–69 years for thyroid cancer without invasion. Approximately one-half of patients experienced long-term use of a tracheal tube and/or multiple operations for tracheal reconstruction. Conclusion The peak incidence of tracheal invasion from thyroid cancer was observed at ages of >70 years. In addition, conventional surgical management appears to be limited in its ability to reconstruct tracheal defects.