Thyroid Gland Management in Total Laryngectomy: Meta-analysis

Abstract

Objective 1. Review the incidence of thyroid gland invasion by squamous cell laryngeal carcinoma in the literature. 2. Correlate thyroid gland invasion with anatomical characteristics of the laryngeal tumor. Do laryngeal tumors which invade the thyroid gland share certain characteristics which can aid in determing the management of the thyroid gland during total laryngectomy? Methods Systematic review of MEDLINE (1967–2007) and EMBASE (1980–2007) for all total laryngectomy series which commented on thyroid gland invasion according to tumor subsite and pathological characteristics. These results were supplemented with 61 patients from our centers who underwent total laryngectomy with hemi- or total thyroidectomy. Eleven series in total (n = 535) were included in the meta-analysis (fixed effects model). Results Thyroid gland invasion was present in 47 laryngectomy specimens (9%); the main method of invasion of the gland was by direct extralaryngeal extension. Subglottic extension > 10mm (OR 6.27 [2.16 to 18.19]; p = 0.0007), subglottic subsite (OR 4.32 [1.53 to 12.19]; p = 0.006), and transglottic subsite (OR 4.10 [1.75 to 9.57]; p = 0.001) were significantly correlated with thyroid gland invasion. Cartilagenous invasion by tumor was not a significant predictor of thyroid gland invasion (p>0.05). Conclusions Thyroid gland invasion is not a general feature of squamous cell laryngeal carcinoma. When present, it is strongly associated with anteroinferior spread of laryngeal tumors. Thyroidectomy should only be performed during total laryngectomy for transglottic tumors, subglottic tumors, and tumors with subglottic extension >10mm. In these cases, total thyroidectomy is warranted to maximize locoregional control.