Background and objectives: The incidence of thyroid gland involvement in laryngopharyngeal cancer ranges from 0 to 23%. Therefore, ipsilateral hemithyroidectomy and isthmusectomy are routinely performed with total laryngectomy in many clinics. Hemithyroidectomy causes hypothyroidism in 63% of patients, and if combined with radiotherapy, the incidence increases to 89% of patients. But there is no consensus about using thyroid surgery in the treatment of laryngopharyngeal cancer. The purpose of this study was to identify criteria to use in the decision of whether, in cases of laryngopharyngeal cancer, hemithyroidectomy should be performed with total laryngectomy.
Materials and methods: The study group consisted of 28 patients with a mean age of 63.2 years (range 42-77 years). All patients were treated by thyroidectomy with total laryngectomy. We evaluated the incidence of thyroid gland invasion, clinical predisposing factors, pathologic features, and prognosis in cases of laryngopharyngeal cancer.
Results: The incidence of thyroid gland invasion was 14% (4/28). Subglottic extension was the only statistically significant factor in thyroid invasion. All cases of laryngopharyngeal cancer that invaded the thyroid gland had vocal cord fixation, anterior commissure invasion, and were advanced stage. The most common mechanism of spread to the thyroid was by direct extension through thyroid cartilage and anterior commissure. While the prognosis of patients with thyroid gland invasion was worse than that of patients with no invasion, the difference was not statistically significant.
Conclusion: Prophylactic thyroidectomy should be performed in cases of laryngopharyngeal cancer where there is subglottic extension of the tumor.