Rationale behind thyroidectomy in total laryngectomy: analysis of endocrine insufficiency and oncological outcomes.

Abstract

Thyroidectomy conventionally accompanies total laryngectomy. This study intends to analyze the incidence and factors leading to thyroid gland involvement in carcinoma larynx and hypopharynx. Retrospective chart review from March 2011 to December 2016 of all patients who had undergone total laryngectomy at our institute. A total of 125 patients entered into the analysis. Subsites involved were glottis (n =32), supraglottis (n= 28), transglottis (n= 52), pyriform sinus (n= 12), and subglottis (n= 1). TNM distribution according to AJCC 7th edition is as follows: T2 (n = 1), T3 (n= 34), T4 (n= 90); N0 (n = 97), N1 (n = 13), N2a (n = 5), N2b (n = 5), N2c (n = 4), and N3 (n = 1). Total thyroidectomy was performed in 16 patients, near total thyroidectomy in 5, and hemithyroidectomy in 104. Histopathologically thyroid gland involvement was seen in 11/125 (8.8%). The overall incidence of hypothyroidism was 48% (hemithyroidectomy, 43/104; total thyroidectomy, 16/16; near total thyroidectomy, 1/5). The incidence of permanent hypoparathyroidism was 12.8% (total thyroidectomy, 11; hemithyroidectomy, 5). On multivariate analysis (Cox proportional hazards model), extralaryngeal spread into level 6 (HR = 5.5, p = .006, C.I = 1-18.8) and extracapsular extension (HR = 9.3, p= 0.02, C.I = 1.29-67.5) were statistically significant predictors for thyroid gland involvement. Survival analysis of patients with thyroid gland involvement (n= 11) revealed 5-year overall survival (OS) of 100% and 5-year disease-free survival (DFS) of 59.3% compared with patients without thyroid gland involvement, 71% and 51.7%, respectively (median follow-up, 30months). Thyroid gland involvement did not show a statistically significant effect on OS/DFS on multivariate analysis. In view of the endocrine abnormalities and lack of survival benefit seen, thyroidectomy should be performed judiciously during total laryngectomy.