Thyroid dysfunction following combined therapy for laryngeal carcinoma

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

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.

The incidence of thyroid gland invasion in advanced laryngeal squamous cell carcinoma

Introduction

Invasion of the thyroid gland is not a general feature of advanced laryngeal carcinoma. There is no need for performing thyroidectomy in all total laryngectomy cases.

Objectives

To evaluate the frequency of the thyroid gland invasion in patients with advanced laryngeal squamous cell carcinoma submitted to total laryngectomy and thyroidectomy and to determine whether clinical and pathological characteristics of laryngeal carcinoma can predict glandular involvement.

Methods

A retrospective case series with chart review, from March 2009 to January 2018, was undertaken in the the Princess Norah Oncology Center, King Abdul-Aziz Medical City, Jeddah/KSA. An inception cohort of 56 patients with laryngeal squamous cell carcinoma was considered. Nine cases were excluded. All patients had advanced stage cancer of the larynx (clinically T3‒T4) and underwent total laryngectomy in association with thyroidectomy. Total thyroidectomy was performed in all bilateral lesions or if there was suspicion of contralateral lobe involvement. Hemithyroidectomy was performed in all lateralized lesions. Retrospective histopathologic analysis of thyroid specimens was subsequently performed. The frequency of thyroid gland invasion was calculated and analysis of demographic, clinical and pathological characteristics associated with thyroid gland invasion was performed.

Results

In all, 47 patients underwent total laryngectomy (40 treated with primary laryngectomy and seven treated with salvage laryngectomy following radiation failure or chemoradiation failure). Hemithyroidectomy was performed in 42 patients and the total thyroidectomy was performed in five patients. The overall frequency of invasion of the thyroid gland was 4.3%. Glandular involvement was seen in one advanced transglottic squamous cell carcinoma and one subglottic. In spite of thyroid cartilage invasion in 25.5% of cases detected in the preoperative radiological imaging, only one case demonstrated microscopic thyroid gland invasion.

Conclusions

Thyroidectomy may only be required during total laryngectomy for selected cases of advanced transglottic tumors and tumors with subglottic extension more than 10 mm.

The incidence of thyroid dysfunction following radiotherapy for early stage carcinoma of the larynx

External beam radiotherapy is currently the commonest form of treatment for early laryngeal cancer (T1/2) and thyroid dysfunction is a well recognised complication of this treatment. Overt hypothyroidism is a specific clinical disorder which in most patients will be recognized and treated. The problems associated with subclinical hypothyroidism (elevated TSH with normal T4), however, are only now being recognized and their management is to some extent still controversial. The aims of our study are to determine the incidence of clinical and subclinical hypothyroidism in those who have been treated solely with curative radiotherapy for early laryngeal cancer. We performed a retrospective observational study encompassing all patients who underwent curative radiotherapy for T1/T2 laryngeal cancer between 1998 and 2002. 33 patients were identified (mean 66.85 years, range 48-93). 19 patients had T1 lesions (58%), 14 had T2 lesions (42%) and 27 were N0 (82%). 23 patients were euthyroid post treatment (70%), 2 became overtly hypothyroid (6%) and 8 developed subclinical hypothyroidism (24%). There was no association between tumour stage (p = 0.97), nodal stage (p = 0.46) and thyroid status, however, there was an association between increasing age and deteriorating thyroid function (p = 0.01). Our study showed that of patients with early laryngeal cancers treated solely with curative radiotherapy 24% developed subclinical hypothyroidism and 6% were overtly hypothyroid (Elevated TSH and reduced T4). We feel patients should receive regular thyroid function testing following completion of treatment and should be adequately counselled on the risk of thyroid dysfunction following radiotherapy at pre-treatment visits.

Management of thyroid gland invasion in laryngopharyngeal cancer

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.

Hypothyroidism when the thyroid is included only in the low neck field during head and neck radiotherapy

OBJECTIVE

The minimum dose required to electively irradiate all of part of the low neck for squamous cell carcinoma of the oropharynx is 50 Gy in 25 fractions or its radiobiological equivalent. The purpose of our study is to determine the incidence of hypothyroidism when the thyroid is treated only in the low-neck radiotherapy (RT) field to approximately 50 Gy.

METHODS AND MATERIALS

390 patients with oropharyngeal carcinoma received RT between 1990 and 2000, had no prior thyroid disease or surgery, and had RT involving the standard anterior low-neck field including the thyroid with a dose equivalent to 50 Gy at 2Gy/fx with or without a boost to a portion of the field to 60 to 70 Gy. The end point was hypothyroidism defined as thyroid stimulating hormone (TSH) above the upper limit of the normal range.

RESULTS

As we did not routinely monitor TSH during this study, it was obtained in 169 of 390 patients. Median follow-up on all 390 patients was 6.1 years. The incidence of hypothyroidism was calculated for 2 groups: 169 patients with TSH data and the total population of 390 patients. For both analyses, patients were censored at last follow-up if the TSH level was normal, or if TSH was not checked. The incidence of hypothyroidism at 5 years was 31% for all 390 patients and 54% for the subset of 169 patients with TSH data. Adjuvant chemotherapy and/or planned neck dissection may be associated with a small increased risk of hypothyroidism.

CONCLUSIONS

Including the thyroid in the low-neck field to 50 Gy results in hypothyroidism in 30% to 50% of patients at 5 years, suggesting that the threshold for this complication is <50 Gy.

Predictors of Thyroid Gland Invasion in Glottic Squamous Cell Carcinoma

OBJECTIVE

This study examines preoperative clinical and intraoperative histopathologic characteristics that can be used to predict thyroid gland invasion in the setting of squamous cell carcinoma (SCC) of the glottis.

STUDY DESIGN

The study was retrospectively performed using 30 serially sectioned whole-organ total laryngectomy with thyroidectomy specimens with associated preoperative clinical data.

METHODS

Histopathologic and clinical variables including true vocal cord (TVC) fixation, cricoarytenoid joint invasion, subglottic extension (SGE) of tumor, patterns of laryngeal spread, and prior radiation were examined as univariate and multivariate correlates of thyroid gland invasion.

RESULTS

Twenty-three percent of thyroid gland specimens demonstrated SCC invasion. Five were T4 stage, two were T3 stage, and all demonstrated direct extension to the thyroid gland. Of these, all had a fixed ipsilateral TVC (P = .003) and SGE of tumor greater than 15 mm (P = .003). Using multivariate analysis, SGE of tumor and TVC fixation contribute independently as correlates of thyroid gland invasion. Prior radiation of the larynx did not correlate with thyroid gland invasion and did not significantly influence the predictive capacity of these variables. Tumors invading the thyroid gland also invaded the cricothyroid membrane (100%), anterior commissure (100%), laryngeal ventricle (100%), and thyroid cartilage (86%).

CONCLUSION

Preoperative assessment of TVC mobility and extent of SGE are significant correlates of thyroid gland invasion by SCC of the glottis. Distinct patterns of laryngeal spread are associated with thyroid gland invasion. Prophylactic hemithyroidectomy with isthmusectomy is indicated for glottic SCC in the preoperative setting of a fixed TVC and SGE greater than 15 mm. Additional study correlating patterns of laryngeal spread with thyroid gland invasion will add to these data in determining when to selectively perform thyroidectomy in this setting.

Thyroid Function Should Be Monitored Following Radiotherapy to the Low Neck

The purpose of this study was to determine whether the incidence of hypothyroidism following radiotherapy (RT) to the low neck is high enough to justify the routine monitoring of thyroid function in asymptomatic patients. A retrospective study of 504 patients with head and neck cancer whose RT fields included the thyroid gland was conducted. Patients were treated either with definitive or postoperative RT. Hypothyroidism was defined as a thyroid stimulating hormone (TSH) level > or =4.5 mIU/L, regardless of whether the patient had clinical symptoms. Of the 504 total patients, 206 had a serum TSH level checked at some point posttreatment. If we assume that patients who had no data did not have hypothyroidism, the actuarial freedom from hypothyroidism in the entire group was 78% at 5 years and 51% at 10 years. Of the 206 patients who had a documented posttreatment TSH, the actuarial freedom from hypothyroidism was 58% at 5 years and 26% at 10 years. Univariate analysis and multivariate analysis confirmed treatment modality to be a significant predictive factor. Definitive initial surgery that removed part of the thyroid gland increased the risk of developing hypothyroidism. Overall stage was also predictive on multivariate analysis. Head and neck irradiation results in biochemical hypothyroidism in at least 50% of patients. Thyroid function should be tested on a regular basis following RT to the low-neck region. Serum TSH should be checked every 6 months for the first 5 years and yearly thereafter. Thyroid hormone replacement should be initiated in any patient with a TSH of more than 4.5 mIU/L.

Thyroid Function Studies in Patients with Cancer of the Larynx: Preliminary Evaluation

OBJECTIVE: Our goal was to evaluate thyroid function before and after surgery only or radiotherapy plus surgery for laryngeal neoplasms.

STUDY DESIGN AND SETTING: The study group consisted of a total of 30 patients with laryngeal cancer (22 treated with surgery only and 8 treated with surgery plus radiotherapy) who were evaluated by ultrasensitive thyroid-stimulating hormone, free T4, and antithyroid antibodies both preoperatively and at 6 and 12 months after surgery.

RESULTS: All patients had normal thyroid function before treatment (1 patient had elevated antithyroid autoantibodies); after 1 year, 4 (13.34%) patients were hypothyroid. In 3 patients, it was sub-clinical (ie, elevated thyroid-stimulating hormone with normal free T4), and in 1 patient, it was symptomatic.

CONCLUSION: Our preliminary data suggest that hypothyroidism occurs in a small but substantial proportion of patients undergoing surgery with or without adjuvant radiotherapy for laryngeal cancer.

SIGNIFICANCE: Thyroid hormone dosing should be routinely included in the assessment of patients with laryngeal cancer, because it is simple and inexpensive and may allow the early diagnosis and management of hypothyroidism. (Otolaryngol Head Neck Surg 2003;129:733-8.)

Hypothyroidism after radiotherapy for laryngeal cancer

PURPOSE

To investigate the incidence of hypothyroidism after radiotherapy of laryngeal cancer, including the possible factors that could predict the onset of hypothyroidism.

MATERIALS AND METHODS

We report this study on patients treated by radiotherapy as part of the treatment for laryngeal cancer in the Department of Oncology in Eastern Finland. Sixty-five males and seven females were treated with radiotherapy between 1974-1995.Thyroid function was determined by measuring serum thyroid stimulating hormone, and serum free thyroxine (FT4). The studied risk factors for hypothyroidism included age, treatment modalities, radiation dose and energy, height of the radiation field, and follow-up time.

RESULTS

Hypothyroidism was detected in 17 (24%) of the 72 patients. Hypothyroidism was clinically unsuspected in all but one patient. Hypothyroidism was more common, if the height of the radiation field was >/=7 cm, or the patient had been operated. Hypothyroidism was less common if less than a half of the thyroid bed was irradiated.

CONCLUSION

The detection of hypothyroidism clinically is difficult, and the rate of hypothyroidism warrants routine assessment of thyroid function after irradiation of laryngeal cancer.

Hypothyroidism after therapy for larynx and pharynx carcinoma

Early detection of local and regional recurrence is the main goal during follow-up of patients with larynx and pharynx cancer. Hypothyroidism occurring in those patients stays frequently undiagnosed as screening for hypothyroidism is not part of the routine follow-up. This study was performed to assess the prevalence of hypothyroidism in these patients. We included 120 patients (106 male, 14 female) with larynx or pharynx cancer treated more than 2 months earlier (mean = 41 months) in the study. Cancer treatment consisted of either surgery (n = 44), radiotherapy (n = 15), or surgery combined with postoperative radiotherapy (n = 61). In all patients, thyroid function studies (thyrotropin [TSH], free triiodothyronine [FT3], and free thyroxine [FT4]) were performed. Twenty-six of all patients (22%) were hypothyroid; in two patients hypothyroidism was diagnosed postoperatively and these two patients were on replacement therapy with thyroid hormones. The highest rate of hypothyroidism (34%) was present in patients treated with surgery combined with radiotherapy, whereas among patients treated with surgery only 7% were hypothyroid (p < 0.001). There was no difference in the duration of follow-up between therapy and inclusion in the study between those two groups. Two of 15 patients treated only with radiotherapy were diagnosed hypothyroid, but in this group the latency was shorter (p < 0.05). The results indicate that thyroid function studies should be routinely performed in the follow-up of head and neck cancer patients, especially if radiotherapy was part of the treatment.