Hypothyroidism following combined treatment for hypopharyngeal and laryngeal carcinoma

Correlation of Preoperative Radiological Factors with Histological Involvement of Thyroid Gland in Laryngeal Carcinomas

Total laryngectomy is the primary treatment for locally advanced laryngeal carcinomas. However, routine thyroid removal (total or hemithyroidectomy) during this procedure is controversial, as the incidence of thyroid gland involvement varies and may lead to lifelong thyroid supplementation, increasing postoperative morbidity. The lack of a consensus on managing the thyroid gland in laryngeal carcinoma cases necessitates improved evaluation techniques, with radiology playing a crucial role in this aspect. Understanding the correlation between radiological factors and histopathological involvement of the thyroid gland can aid in formulating appropriate management strategies during total laryngectomy. To study the correlation of preoperative radiological factors with histopathological involvement of thyroid gland in laryngeal carcinomas. This was a retrospective study which included 57 patients who underwent total laryngectomy for squamous cell carcinoma of larynx. The pre-operative CT findings such as involvement of thyroid cartilage, cricoid cartilage, paraglottic space, anterior commissure, subglottis and thyroid gland along with transglottic extension of tumor were correlated with post-operative histopathological thyroid gland involvement. Cricoid cartilage erosion and thyroid gland involvement in CT scans individually exhibited positive likelihood ratios of 2.58 and 3.23, respectively, demonstrating a reasonable agreement with histopathological findings. The specificity of cricoid cartilage and thyroid gland involvement was also higher with values of 76.4% and 81%, respectively. Moreover, combining thyroid and cricoid cartilage erosion in CT scans as a predictive parameter for thyroid gland involvement resulted in a better likelihood ratio of 8.23 and a fair agreement with histopathological findings. We conclude that cricoid cartilage erosion and thyroid gland involvement in pre-operative CECT can be taken as a preoperative indicator for intraoperative decision on thyroidectomy.

Does thyroid-sparing total laryngectomy decrease the risk of hypothyroidism?

BACKGROUND

Thyroid lobectomy is recommended with total laryngectomy for laryngeal cancer in the National Comprehensive Cancer Network ('NCCN') guidelines. However, it is associated with a 32-89 per cent risk of hypothyroidism, with or without adjuvant radiotherapy.

OBJECTIVE

The study aimed to determine whether preserving the whole thyroid, compared to a single lobe, does indeed significantly lower the incidence of hypothyroidism in the setting of total laryngectomy.

METHOD

A retrospective study was conducted at Groote Schuur Hospital in Cape Town, South Africa.

RESULTS

Eighty-four patients met the inclusion criteria. The overall incidence of hypothyroidism was 45.2 per cent. The incidence of hypothyroidism was significantly reduced in patients who underwent thyroid-sparing total laryngectomy compared to hemithyroidectomy (p = 0.037). Adjuvant radiotherapy was associated with a higher incidence of hypothyroidism (p = 0.001).

CONCLUSION

Thyroid-preserving laryngectomy should be advocated in carefully selected patients with advanced laryngeal carcinoma, as it reduces the incidence of hypothyroidism.

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.

Thyroid dysfunction in laryngectomees—10 years after treatment

BACKGROUND

Hypothyroidism is 1 of the complications that follow treatment of various head and neck cancers. In the literature, reviews using different primary sites and differences in treatment modalities make comparison of post-treatment hypothyroidism not possible. The objective of this study was to evaluate the incidence of hypothyroidism in a homogenous group of patients who were treated with total laryngectomy and irradiation for laryngeal carcinoma and to assess the importance of different variables in the occurrence of hypothyroidism.

METHODS

A retrospective review of 147 total laryngectomy patients between 1993 and 2003 was carried out. Serum thyroxine level and free T4 levels were assessed in all patients. Hypothyroidism was classified as subclinical (increased thyroid-stimulating hormone and normal free T4 levels) and clinical (increased thyroid-stimulating hormone and decreased free T4 levels).

RESULTS

The results showed that the overall incidence of hypothyroidism was 49% (44% subclinical and 5% clinical). Hemithyroidectomy and advanced tumor staging were risk factors for the development of hypothyroidism in these patients (p < .05) with a relative risk of 2.1 (CI 95%, 1.4-3.1) and 1.3 (CI 95%, 1.1-1.6), respectively. During follow-up, 19.9% of patients developed hypothyroidism at 3 years, 38.6% at 6 years; at 10 year follow-up, 93.3% of them had hypothyroidism.

CONCLUSIONS

In conclusion, hypothyroidism is a frequent complication in patients treated with radiotherapy and total laryngectomy for laryngeal cancer, especially when treatment includes hemithyroidectomy. These patients should have their thyroid function evaluated periodically even 10 years after treatment.

Incidence of hypothyroidism after radiotherapy for nasopharyngeal carcinoma

OBJECTIVES

The thyroid gland is frequently affected by radiotherapy applied for the treatment of head and neck tumors. Hypothyroidism is observed as a late side effect of radiotherapy, especially seen in the patients who have surgery in the treatment procedure.

METHODS

We evaluated the radiation-induced hypothyroidism for a selected type of head and neck cancer- nasopharyngeal cancer (NPC)-which does not include surgery involving the thyroid gland in the treatment.

RESULTS

We observed 12 patients (14%) who developed hypothyroidism, two of which were subclinical hypothyroidism. The patients with hypothyroidism were statistically significantly younger than the euthyroid patients, but there were no statistically significant differences among the two groups in disease stages, radiotherapy neck doses, and gender.

CONCLUSIONS

We recommend life-long TSH screening after RT to the neck owing to the incidence of RTinduced hypothyroidism and the importance of early thyroid hormone replacement therapy in patients becoming hypothyroid for maintaining optimal quality of life.

Epidemiology and prevention of clinical and subclinical hypothyroidism

Iodine deficiency is the most common cause of hypothyroidism worldwide. In persons living in iodine-replete areas, causes are congenital, spontaneous because of chronic autoimmune disease (atrophic autoimmune thyroiditis or goitrous autoimmune thyroiditis [Hashimoto's thyroiditis]), or iatrogenic because of goitrogens, drugs, or destructive treatment for thyrotoxicosis. Screening for congenital hypothyroidism exists and its use prevents mental retardation. The prevalence of spontaneous hypothyroidism is between 1% and 2% and is more common in older women and 10 times more common in women than in men. A significant proportion of subjects have asymptomatic chronic autoimmune thyroiditis and 8% of women (10% of women over 55 years of age) and 3% of men have subclinical hypothyroidism. Approximately one third of patients with newly diagnosed overt hypothyroidism have received destructive therapy for hyperthyroidism and indefinite surveillance is required. There is not much that can be done to prevent the occurrence of spontaneous autoimmune hypothyroidism, but if identified early, something can be done to prevent progression to overt disease. Controversy exists as to whether healthy adults would benefit from screening for autoimmune thyroid disease because a significant proportion of subjects tested will have evidence of mild thyroid failure. Case finding in women at menopause or visiting a primary care physician with nonspecific symptoms appears justified.

Risk factors associated with hypothyroidism after laryngectomy

Hypothyroidism is a well-documented complication after treatment of head and neck cancer and is particularly significant among patients undergoing laryngectomy. The objective of this study was the identification of factors associated with the development of hypothyroidism in this population. Records of 136 patients treated with laryngectomy were retrospectively reviewed in an attempt to define a risk factor profile for patients in whom hypothyroidism is most likely to develop after laryngectomy. The Cox proportional hazards model was used to identify factors significantly related to an increased risk for development of hypothyroidism. The actuarial method was used to estimate the period of greatest risk for the development of hypothyroidism. Increased risks were found for patients who were female (P = 0.0049), received preoperative radiation therapy (P = 0.0022), had invasion of the thyroid gland by tumor (P = 0.0003), had presence of cervical metastases (P = 0.0022), and had postoperative fistula (P = 0.0095). From the actuarial method, we estimated that the period of time when patients were at greatest risk for development of hypothyroidism was between 0 and 14 months after surgical intervention. Wound complications were twice as frequent in hypothyroid patients. Perioperative awareness of risk factors associated with the development of hypothyroidism in patients undergoing laryngectomy allows for early recognition and management of hypothyroidism and may reduce the number of complications related to wound healing and fistula.

[Late effects of ionizing radiations on the thyroid gland]

The thyroid is the purest endocrine gland in the body and is likely to produce clinically significant abnormalities after external radiotherapy. Functional clinical modifications after direct irradiation exceeding 30 Gy are essentially related to hypothyroidism which may be clinically overt or subclinical with normal serum free thyroxine levels and high thyrotropin concentrations; the risk of hyperthyroidism, silent thyroiditis and Hashimoto's disease is also increased. Secondary hypothyroidism related to irradiation of the hypothalamus and the pituitary gland may arise with doses over 40-50 Gy following treatment for brain and nasopharyngeal tumors--Morphological glandular modifications induced by radiotherapy are responsible for the appearance of benign adenomas, more rarely cystic degenerations and specially well differentiated papillary or follicular carcinomas among children and adults. After irradiation during childhood for benign or malignant tumors, thyroid cancers are more frequent, higher for younger children, and the relative excess risk is increased from 15.6-to 53-fold; tumors can belatedly occur, more than 35 years after initial therapy. Thereby, in order to limit excess morbidity, it is evident that long term supervision with careful clinical and biological evaluations is necessary for patients who previously received neck, upper mediastinum and pituitary radiation therapy.

Postradiotherapy hypothyroidism: radiation dose response and chemotherapeutic radiosensitization at less than 40 Gy

To analyze our experience with iatrogenic hypothyroidism, we prospectively followed 84 patients, seen from 1984 to 1990, who had been diagnosed with either Hodgkin's disease (HD) or head and neck (H&N) carcinoma and subsequently treated with radiotherapy. Within these two diagnostic groups were subgroups whose treatment differed as to dose of therapeutic irradiation received or adjunctive use of chemotherapy. Approximately 50% of all patients and of each subgroup developed either clinical or subclinical hypothyroidism during follow-up. However, among the HD patients who received irradiation plus chemotherapy, a dose-response relationship below a threshold limit of dose received, probably 40 Gy, was observed.

Thyroidectomy during laryngectomy for advanced laryngeal carcinoma--whole organ section study with long-term functional evaluation

Whole organ step-serial section of laryngectomy specimens was carried out in 16 patients with a T3 and T4 laryngeal carcinoma to study the involvement of the thyroid gland. Three patients (19%) were found to have tumour invasion into the thyroid gland, and two patients (16%) were found to have tumour on the thyroid capsule. Of the 12 patients who had tumour involving the subglottic region, five patients were found to have involvement of the thyroid gland. Of the remaining four patients without subglottic tumour extension, none had tumour involvement of the thyroid gland. Of the five patients who had long-term survival of 10 years, two patients had subclinical hypothyroidism and one patient had clinical hypothyroidism. We recommend routine hemithyroidectomy when the subglottic region is involved by tumour. The whole thyroid gland should be preserved when the laryngeal tumour is confined to the supraglottic and glottic regions without clinical evidence of thyroid gland involvement.