Thyroid Dysfunction after Combined therapy for Laryngeal Cancer: A Prospective Study

Incidence and complications of hypothyroidism postlaryngectomy: A systematic review and meta-analysis

BACKGROUND

Hypothyroidism is common postlaryngectomy and is associated with laryngectomy-specific complications. The objective of this study is to determine the incidence and predictors of hypothyroidism postlaryngectomy and its associated complications.

METHODS

Systematic review, data extraction, and meta-analyses were performed following the PRISMA protocol. Six databases were searched for studies reporting on postlaryngectomy thyroid status with incidence, risk factors, management, or complications.

RESULTS

Fifty-one studies with 6333 patients were included. The pooled incidence of postlaryngectomy hypothyroidism is 49% (CI 42%-57%). Subgroup analysis showed postlaryngectomy hypothyroidism rates significantly correlated with hemithyroidectomy and radiotherapy. Patients who underwent laryngectomy, hemithyroidectomy, and radiotherapy had a 65% (CI 59%-71%) rate of hypothyroidism; laryngectomy and hemithyroidectomy 46% (CI 33%-60%); laryngectomy and radiotherapy 26% (CI 19%-35%); and laryngectomy alone 11% (CI 4%-27%) (p < 0.001).

CONCLUSIONS

Laryngectomized patients with partial thyroidectomy or radiation therapy are at significant risk of postoperative hypothyroidism. Evidence-based protocols for early detection and (prophylactic) treatment should be established.

Incidence of Post Total Laryngectomy Hypothyroidism: Effects of Thyroid Gland Surgery and Post-Operative Radiotherapy

To record the incidence of hypothyroidism in patients after total laryngectomy, whether with or without postoperative radiation therapy and to analyze the effect of hemithyroidectomy for the development of hypothyroidism. A retrospective study included patients who underwent total laryngectomy (with or without hemithyroidectomy) between 2018 and 2021 for laryngeal carcinoma and/or received postoperative radiotherapy. Thirty-six (45%) of the 80 enrolled patients developed hypothyroidism after a median follow-up of 16 months. In this study, adjuvant radiation and central neck dissection were found to be significantly linked with developing post-operative hypothyroidism (p values: 0.001, 0.007, respectively). The incidence of hypothyroidism in patients treated for laryngeal carcinoma is high, especially after combination treatment of surgery and radiotherapy.

Determining the Occurrence of Hypothyroidism Following Treatment With Radiation Therapy in Head and Neck Carcinoma Patients and the Associated Role of Risk Factors and Dose-Volume Histograms: A Prospective Study

Background

Head and neck carcinomas are one of the most common malignancies in developing countries including India. Most patients are treated with radiotherapy. Although post-radiotherapy hypothyroidism is a known complication, data regarding its incidence and factors influencing it are scarce. This study aimed to determine the incidence of post-radiotherapy hypothyroidism in head and neck carcinoma patients treated with radiotherapy and the factors influencing it.

Methodology

Patients with head and neck carcinomas treated with radiotherapy as one of the modalities were included in this study. Thyroid function tests were done, and quality of life questionnaires were completed before treatment and during follow-up. Dose-volume histogram (DVH), demographic data, and disease-related parameters were compared.

Results

Out of the 95 patients screened, 14 were found to be hypothyroid prior to the commencement of radiotherapy and were excluded. With a median follow-up duration of 34 weeks, 29.6% developed hypothyroidism, with 19% developing it in the first year. On univariate and multivariate analysis of the DVH of the thyroid gland, volume receiving 50 Gy (V50), dose received to 50% volume (D50), and the mean dose (more than 50 Gy) were found to be significantly associated with hypothyroidism.

Conclusions

Hypothyroidism is a significant comorbid factor in Indian patients with head and neck carcinomas. The incidence of post-radiotherapy hypothyroidism is significant and occurs early compared to the western population leading to significant deterioration in the quality of life. Parameters such as the volume of the thyroid gland, V50, D50, and mean dose to the thyroid gland influence the incidence of hypothyroidism. The use of appropriate constraints can significantly prevent radiotherapy-induced hypothyroidism.

Thyroid-optimized and thyroid-sparing radiotherapy in oral cavity and oropharyngeal carcinoma: A dosimetric study

BACKGROUND

Radiation-induced hypothyroidism is a common toxicity of head and neck radiation. Our re-planning study aimed to reduce thyroid dose while maintaining target coverage with IMRT.

METHODS

We retrospectively identified patients with oral-cavity (n = 5) and oropharyngeal cancer (n = 5). Treatment plans were re-optimized with 45 Gy thyroid mean dose constraint, then we cropped the thyroid out of PTVs and further reduced thyroid dose. Target coverage was delivering 100% dose to ≥ 93% of PTV and 95% of dose to > 99% of PTV.

RESULTS

Originally, average mean dose to thyroid was 5580 cGy. In model I, this dropped to 4325 cGy (p < 0.0001). In model II, average mean dose was reduced to 3154 cGy (p < 0.0001). For PTV low and PTV int, all had acceptable target coverage.

CONCLUSION

In patients with oral-cavity and oropharyngeal cancers, mean dose could be significantly reduced using a thyroid-optimized or thyroid-sparing IMRT technique with adequate coverage.

Guidelines for the Surgical Management of Laryngeal Cancer: Korean Society of Thyroid-Head and Neck Surgery

Korean Society of Thyroid-Head and Neck Surgery appointed a Task Force to develop clinical practice guidelines for the surgical treatment of laryngeal cancer. This Task Force conducted a systematic search of the EMBASE, MEDLINE, Cochrane Library, and KoreaMed databases to identify relevant articles, using search terms selected according to the key questions. Evidence-based recommendations were then created on the basis of these articles. An external expert review and Delphi questionnaire were applied to reach consensus regarding the recommendations. The resulting guidelines focus on the surgical treatment of laryngeal cancer with the assumption that surgery is the selected treatment modality after a multidisciplinary discussion in any context. These guidelines do not, therefore, address non-surgical treatment such as radiation therapy or chemotherapy. The committee developed 62 evidence-based recommendations in 32 categories intended to assist clinicians during management of patients with laryngeal cancer and patients with laryngeal cancer, and counselors and health policy-makers.

Correlative study of dose to thyroid and incidence of subsequent dysfunction after head and neck radiation

BACKGROUND

Thyroid dysfunction is common after radiotherapy (RT) for patients with head and neck cancers. We attempted to discover RT dose parameters that correspond with RT-induced thyroid dysfunction.

METHODS

Records of 102 patients who received RT from 2008 to 2010 were reviewed with respect to thyroid function. Abnormalities were grouped in 2 ways: (1) none, transient, or permanent; and (2) overt or subclinical.

RESULTS

At median follow-up of 33.5 months, incidence of any thyroid abnormality was 39.2% (women vs men - 50% vs 35%). Permanent dysfunction was seen in 24.5% with higher incidence in women versus men (42.9% vs 17.6%; p = .0081). Permanent abnormalities most strongly correlated with D_50% (p = .0275). V_50Gy also correlated with thyroid dysfunction post-RT (p = .0316). Concurrent chemotherapy increased permanent dysfunction (p = .0008).

CONCLUSION

Achieving D_50% <50 Gy, V₅₀ <50%, and mean dose <54.58 Gy during RT planning may decrease the incidence; whereas female sex and concurrent chemotherapy seem to increase the risk of RT-induced hypothyroidism. © 2016 Wiley Periodicals, Inc. Head Neck 39: 548-554, 2017.

Hypothyroidism in patients treated with radiotherapy for head and neck carcinoma: standardised long-term follow-up study

OBJECTIVE

Hypothyroidism is a common complication when radiotherapy is part of the treatment for head and neck tumours. This study aimed to show the incidence of hypothyroidism and possible risk factors in these patients.

METHODS

Factors related to the population, tumour, treatment and occurrence of hypothyroidism were analysed in 241 patients diagnosed with head and neck carcinoma.

RESULTS

Approximately 53 per cent of patients were diagnosed with radiation-induced hypothyroidism. Its occurrence was related to: tumour location, laryngeal surgery type, neck dissection type, post-operative complications, cervical radiotherapy and radiotherapy unit type (linear particle accelerator or telecobalt therapy technology).

CONCLUSION

Control of thyroid function should be standardised for several years after treatment, particularly in patients with risk factors, such as those treated with telecobalt therapy, those with post-operative complications and for whom the thyroid parenchyma is included in the irradiated area (laryngeal or pharyngeal location and bilateral cervical radiation).

A prospective longitudinal study on endocrine dysfunction following treatment of laryngeal or hypopharyngeal carcinoma

OBJECTIVES

The incidences of hypo(para)thyroidism were assessed prospectively in 137 consecutive patients with laryngeal (84.7%) or hypopharyngeal (15.3%) carcinoma who were treated with surgery and/or radiotherapy between 2004 and 2006.

MATERIAL AND METHODS

Laboratory studies were performed in patients before primary or salvage treatment of a laryngeal or hypopharyngeal carcinoma and were repeated 6, 12, 18 and 24months after treatment. All patients were evaluated for the development of hypo(para)thyroidism, and the presence of autoantibodies. The association of hypothyroidism was analyzed against several patient parameters including tumor and treatment characteristics.

RESULTS

The incidence of hypothyroidism following treatment of laryngeal and hypopharyngeal carcinoma was 47.4%: 27.7% subclinical hypothyroidism and 19.7% clinical hypothyroidism. The median time to develop hypothyroidism was 10months. The incidence of hypoparathyroidism was 7.3%. Univariate analysis showed that patients with laryngectomy, hemithyroidectomy, neck dissection, paratracheal lymph node dissection and radiotherapy had a higher risk of developing hypothyroidism. Multivariate analysis showed laryngectomy, hemithyroidectomy, neck dissection and age to be predictive factors for the development of hypothyroidism. The combination of surgery and radiotherapy increased this risk. Hemithyroidectomy was the most important risk factor.

CONCLUSION

The incidence rate of hypothyroidism after treatment for laryngeal or hypopharyngeal cancer in this largest prospective study is high (47.4%), especially after combination treatment. Based on the intervals between treatment and the development of hypothyroidism, thyroid testing before treatment, every 3months during the first year, every 6months the second year and annually thereafter is recommended as screening procedure.

A prospective cohort study on radiation-induced hypothyroidism: development of an NTCP model

PURPOSE

To establish a multivariate normal tissue complication probability (NTCP) model for radiation-induced hypothyroidism.

METHODS AND MATERIALS

The thyroid-stimulating hormone (TSH) level of 105 patients treated with (chemo-) radiation therapy for head-and-neck cancer was prospectively measured during a median follow-up of 2.5 years. Hypothyroidism was defined as elevated serum TSH with decreased or normal free thyroxin (T4). A multivariate logistic regression model with bootstrapping was used to determine the most important prognostic variables for radiation-induced hypothyroidism.

RESULTS

Thirty-five patients (33%) developed primary hypothyroidism within 2 years after radiation therapy. An NTCP model based on 2 variables, including the mean thyroid gland dose and the thyroid gland volume, was most predictive for radiation-induced hypothyroidism. NTCP values increased with higher mean thyroid gland dose (odds ratio [OR]: 1.064/Gy) and decreased with higher thyroid gland volume (OR: 0.826/cm(3)). Model performance was good with an area under the curve (AUC) of 0.85.

CONCLUSIONS

This is the first prospective study resulting in an NTCP model for radiation-induced hypothyroidism. The probability of hypothyroidism rises with increasing dose to the thyroid gland, whereas it reduces with increasing thyroid gland volume.

Factors associated with the development of new onset diffuse thyroid F18-fluorodeoxyglucose uptake after treatment of breast cancer in patients without a history of thyroid disease or thyroid dysfunction

BACKGROUND

Many studies have shown an association between thyroid disorders and breast cancer. Among them, diffusely increased thyroid uptake of F18-fluorodeoxyglucose (F-18 FDG) has been associated with chronic lymphocytic thyroiditis. There is little or no information regarding the relationship between treatment of breast cancer and the development of new diffuse thyroid F-18 FDG uptake. Here, we report the frequency of this occurrence and some of the factors associated with it.

METHODS

We performed a retrospective review of the positron emission tomography (PET) computed tomography (CT) database and identified 290 women who had underwent PET-CTs both before and after breast surgery. Of these, 246 were enrolled in this study and 44 were excluded, because before breast surgery they had either a history of prior thyroid disorders including thyroid cancer or abnormal serum free thyroxine and thyroid-stimulating hormone, or other malignancies. Tests for serum antithyroid antibodies were not available before thyroid surgery in all patients. There were 62 patients who did have antithyroid antibody tests before surgery and 27 were positive. They were not excluded from the study.

RESULTS

Diffuse thyroidal uptake on PET-CT developed in 23 (9.3%) patients during the follow-up period (median=21.1 months; range=3.1-47.3 months). Age (≥55 years; hazard ratio [HR]=0.15; 95% confidence interval [CI]: 0.03-0.65; p=0.012), bilaterality of breast cancer (HR=3.87; 95% CI: 1.02-14.62; p=0.046), and postsurgical radiotherapy (HR=3.06; 95% CI: 1.03-9.16; p=0.045) showed independent association with new thyroid FDG uptake in multivariate analysis. All patients with thyroid FDG uptake met at least one of some criteria related to chronic thyroditis (positive for antithyroid antibodies or cytology findings or ultrasonography findings of Hashimoto's thyroiditis) and were associated with development of hypothyroidism (52.2% vs. 4.5% in patients without uptake; p<0.001).

CONCLUSIONS

Radiotherapy in breast cancer may be an independent predictive factor for the development of new diffuse thyroidal uptake in PET-CT associated with thyroid dysfunction during follow-up. The development of diffuse F-18 FDG uptake is a marker for thyroid abnormalities. Younger women who have radiotherapy after surgery for breast cancer, in particular, are candidates for close follow-up of their thyroid function.

Thyroid gland involvement in advanced laryngeal cancer: association with clinical and pathologic characteristics

BACKGROUND

Indications for thyroidectomy during laryngectomy are controversial. We examined whether clinicopathologic features can predict thyroid gland involvement, and the prognostic effect of thyroid gland involvement in patients undergoing total laryngectomy.

METHODS

The study set out to review preoperative assessment, operation findings, pathologic findings, and follow-up data.

RESULTS

Thyroid gland involvement was found in 11 of 53 patients (21%) undergoing total laryngectomy and thyroidectomy. Preoperative work-up failed to predict thyroid gland involvement. Thyroid gland involvement was associated with salvage procedures (p = .025), paratracheal metastases (p = .003), and poor overall survival (hazard ratio = 2.74, p = .008).

CONCLUSIONS

Thyroid gland involvement in patients undergoing total laryngectomy is frequent and is associated with poor prognosis. Preoperative assessment failed to predict thyroid gland involvement. We believe that thyroidectomy should be considered in cases with paratracheal lymphatic spread irrespective of tumor location within the larynx.

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.