Frequency of Thyroid Gland Invasion by Laryngeal Squamous Cell Carcinoma: The Role of Subglottic Extension

Abstract

Introduction Management of the thyroid gland during laryngectomy has been controversial. The primary tumor may invade the thyroid gland by direct invasion or lymphovascular spread. Hypothyroidism and hypoparathyroidism are potential risks when lobectomy or total thyroidectomy are performed simultaneously. Objective To report the frequency of thyroid gland involvement by primary laryngeal squamous cell carcinoma in patients undergoing laryngectomy and to identify possible risk factors for thyroid gland involvement so that judicious excision of thyroid gland can be attained. Methods We performed a retrospective review of 9 years. Data was collected from medical records of patients dated from December 2009 to October 2018. All patients with laryngeal cancer who underwent laryngectomy with lobectomy or total thyroidectomy were included in the present study. Results We reviewed 151 laryngectomy records. A total of 130 surgeries included the thyroid gland with the excised specimen and were available for analysis. There were 124 males and 6 females. The mean age was 59.4 years old. The glottis was the most common subsite involved, in 70 patients, followed by 38 transglottic, 16 supraglottic and 03 subglottic tumors. On histology, 12 out of 130 excised thyroid glands were involved by squamous cell carcinoma. Only subglottic involvement (p = 0.01) was significantly associated with thyroid gland invasion (TGI). Type of laryngectomy, subsite of the primary tumor, thyroid cartilage involvement, neck nodal metastases, and perineural and lymphatic invasion by the primary tumor were not associated with TGI. Conclusion Only subglottic involvement is associated with TGI; therefore, preoperative and intraoperative assessment is necessary prior to considering excision of the thyroid gland.

Primary Total Laryngectomy for Endolaryngeal cT3‐4M0 Squamous Cell Carcinoma: A STROBE Analysis

“…Likewise, Semdaie et al 25 advised against performing tracheotomy in case of dyspnea and, like ourselves, prefer CO 2 laser endolaryngeal debulking, in view of the greater perineural tumor infiltration associated with prior tracheotomy, jeopardizing the resection margins. Thyroid resection performed in 43% of the present cases, during TL, had no impact on local recurrence (Table II) and like several authors 26–32 focusing on the issue, we believe that, in endolaryngeal cT3‐4 SCC, thyroid resection is indicated mainly for transglottic or subglottic tumor and/or if subglottic extension exceeds 10 mm and/or involves the cricothyroid membrane. In a meta‐analysis in 2009, Mendelson et al 26 reported 8% thyroid gland involvement by endolaryngeal SCC treated by TL, making direct contiguity the main mechanism of thyroid involvement.…”

“…These authors considered that the overall incidence of thyroid gland invasion was low and advised to consider thyroidectomy for cases deemed risky rather than as a routine measure of TL. 32 Postoperative radiation therapy was used in the 74% of the present cohort and, in our opinion, the absence of significant statistical impact noted on local control (Table II) indicates that it was wisely used in well-selected cases; in SCC without prior tracheotomy, with no subglottic extension and/or with wide R0 margins. Such a policy allows to preserve radiation therapy for subsequent management of head & neck (H &N) metachronous second primaries arising regularly within 10 years after TL (Fig.…”

“…The first two concern the single-center and retrospective design, a limitation however found in almost all the 21st century literature on TL. [8][9][10][11]18,[21][22][23][24][25][26][27][28][29][30][31][32][33][34] The third, and doubtless most important, point concerns to a variety of treatments detailed in the section describing the study population (Table I), with TL performed by 54 different headand-neck surgeons (see Acknowledgments) over a period of 4 decades. However, the local recurrence rate seemed not to vary from decade to decade (Table II), relativizing this bias and suggesting that oncologic results, and notably local recurrence, after TL for endolaryngeal cT3-4 SCC are not operator-dependent.…”

“…In a meta‐analysis in 2009, Mendelson et al 26 reported 8% thyroid gland involvement by endolaryngeal SCC treated by TL, making direct contiguity the main mechanism of thyroid involvement. Furthermore, in a more recent meta‐analysis, Xie et al 32 noted that the risk of thyroid gland invasion was significantly higher when advanced laryngeal cancer involved subglottic tumors, T4 stage tumors, subglottic extension, and thyroid cartilage invasion. These authors considered that the overall incidence of thyroid gland invasion was low and advised to consider thyroidectomy for cases deemed risky rather than as a routine measure of TL 32 .…”

“…Furthermore, in a more recent meta‐analysis, Xie et al 32 noted that the risk of thyroid gland invasion was significantly higher when advanced laryngeal cancer involved subglottic tumors, T4 stage tumors, subglottic extension, and thyroid cartilage invasion. These authors considered that the overall incidence of thyroid gland invasion was low and advised to consider thyroidectomy for cases deemed risky rather than as a routine measure of TL 32 . Postoperative radiation therapy was used in the 74% of the present cohort and, in our opinion, the absence of significant statistical impact noted on local control (Table II) indicates that it was wisely used in well‐selected cases; in SCC without prior tracheotomy, with no subglottic extension and/or with wide R0 margins.…”