MYXOEDEMA AFTER DEEP X-RAY THERAPY TO THE NECK

The incidence of hypothyroidism in patients of head and neck carcinoma treated with radiotherapy and added risk of hypothyroidism with the addition of chemotherapy

Background:

Head and neck cancer (HNC) is the most common malignancy in the Indian males. Most of the cases of HNC present in locally advanced stage and requires a multidisciplinary management approach. Radical or adjuvant external beam radiotherapy (EBRT) is one of the important integral components of the management of HNC.

Aim:

To find the incidence of hypothyroidism (HT) in patients of HNC treated with radiotherapy with or without concurrent chemotherapy.

Methods:

A prospective, single institutional longitudinal observational study conducted at the department of radiotherapy, Institute of Post Graduate Medical Education and Research, Kolkata.

Results:

In this study, data of 118 patients were analysed. The median age at presentation was 56 years. The most common primary site of malignancy was oral cavity (39%). The patients were stage I, stage II and stage III as 11, 37·3 and 51·7% respectively. The median dose of EBRT was 66 Gy. HT statistically significantly correlated with primary site of malignancy (p = 0·001), dose of EBRT (p = 0·005). At the end of follow-up of 6 months, 39·8% developed HT.

Conclusion:

The thyroid gland is an important organ at risk while considering EBRT to neck region. The inclusion of thyroid function test in routine follow-up is mandated.

Measurement of Thyroid Dose by TLD arising from Radiotherapy of Breast Cancer Patients from Supraclavicular Field

BACKGROUND

Breast cancer is the most frequently diagnosed cancer and the leading global cause of cancer death among women worldwide. Radiotherapy plays a significant role in treatment of breast cancer and reduces locoregional recurrence and eventually improves survival. The treatment fields applied for breast cancer treatment include: tangential, axillary, supraclavicular and internal mammary fields.

OBJECTIVE

In the present study, due to the presence of sensitive organ such as thyroid inside the supraclavicular field, thyroid dose and its effective factors were investigated.

MATERIALS AND METHODS

Thyroid dose of 31 female patients of breast cancer with involved supraclavicular lymph nodes which had undergone radiotherapy were measured. For each patient, three TLD-100 chips were placed on their thyroid gland surface, and thyroid doses of patients were measured. The variables of the study include shield shape, the time of patient's setup, the technologists' experience and qualification. Finally, the results were analyzed by ANOVA test using SPSS 11.5 software.

RESULTS

The average age of the patients was 46±10 years. The average of thyroid dose of the patients was 140±45 mGy (ranged 288.2 and 80.8) in single fraction. There was a significant relationship between the thyroid dose and shield shape. There was also a significant relationship between the thyroid dose and the patient's setup time.

CONCLUSION

Beside organ at risk such as thyroid which is in the supraclavicular field, thyroid dose possibility should be reduced. For solving this problem, an appropriate shield shape, the appropriate time of the patient's setup, etc. could be considered.

Alpha lipoic acid attenuates radiation-induced thyroid injury in rats

Exposure of the thyroid to radiation during radiotherapy of the head and neck is often unavoidable. The present study aimed to investigate the protective effect of α-lipoic acid (ALA) on radiation-induced thyroid injury in rats. Rats were randomly assigned to four groups: healthy controls (CTL), irradiated (RT), received ALA before irradiation (ALA + RT), and received ALA only (ALA, 100 mg/kg, i.p.). ALA was treated at 24 h and 30 minutes prior to irradiation. The neck area including the thyroid gland was evenly irradiated with 2 Gy per minute (total dose of 18 Gy) using a photon 6-MV linear accelerator. Greater numbers of abnormal and unusually small follicles in the irradiated thyroid tissues were observed compared to the controls and the ALA group on days 4 and 7 after irradiation. However, all pathologies were decreased by ALA pretreatment. The quantity of small follicles in the irradiated rats was greater on day 7 than day 4 after irradiation. However, in the ALA-treated irradiated rats, the numbers of small and medium follicles were significantly decreased to a similar degree as in the control and ALA-only groups. The PAS-positive density of the colloid in RT group was decreased significantly compared with all other groups and reversed by ALA pretreatment. The high activity index in the irradiated rats was lowered by ALA treatment. TGF-ß1 immunoreactivity was enhanced in irradiated rats and was more severe on the day 7 after radiation exposure than on day 4. Expression of TGF-ß1 was reduced in the thyroid that had undergone ALA pretreatment. Levels of serum pro-inflammatory cytokines (TNF-α, IL-1ß and IL-6) did not differ significantly between the all groups. This study provides that pretreatment with ALA decreased the severity of radiation-induced thyroid injury by reducing inflammation and fibrotic infiltration and lowering the activity index. Thus, ALA could be used to ameliorate radiation-induced thyroid injury.

How common is hypothyroidism after external radiotherapy to neck in head and neck cancer patients?

PURPOSE

To identify the occurrence of clinical and subclinical hypothyroidism among head and neck cancer patients receiving radiation to the neck and to justify routine performing of thyroid function tests during follow-up.

MATERIALS AND METHODS

This is a prospective nonrandomized study of 45 patients of head and neck cancer, receiving radiotherapy (RT). Thyroid stimulating hormone and T4 estimations were done at baseline and at 4 months and 9 months following RT.

RESULTS

Of the 45 patients, 37(82.2 %) were males and eight (17.8 %) were females. All patients received radiation to the neck to a dose of >40Gy. 35.6% received concurrent chemotherapy. Two patients underwent prior neck dissection. Fourteen patients (31.1%) were found to have clinical hypothyroidism (P value of 0.01). Five (11.1%) patients were found to have subclinical hypothyroidism with a total 19 of 45 (42.2%) patients developing radiation-induced hypothyroidism. Nine of 14 patients with clinical hypothyroidism were in the age group of 51 to 60 years (P=0.0522). Five of 16 patients who received chemoradiation and nine of 29 who received RT alone developed clinical hypothyroidism. Above 40 Gy radiation dose was not a relevant risk factor for hypothyroidism.

CONCLUSION

Hypothyroidism (clinical or subclinical) is an under-recognized morbidity of external radiation to the neck which is seen following a minimum dose of 40 Gy to neck. Recognizing hypothyroidism (clinical or subclinical) early and treating it prevents associated complications. Hence, thyroid function tests should be made routine during follow-up.

Hypothyroidism in postradiation head and neck cancer patients: incidence, complications, and management

PURPOSE OF REVIEW

To describe the incidence, risk factors, prevention, and management of hypothyroidism among patients treated with radiation and other modalities for head and neck cancers.

RECENT FINDINGS

Hypothyroidism may occur in up to 48% of patients treated for head and neck malignancies. It has been observed after radiation, surgery, and combined-modality therapies. The onset of hypothyroidism may be as early as 4 weeks and as late as 5 or 10 years after completion of therapy. It has been associated with poor wound healing, bleeding disorders, and a number of other potential complications germane to the practice of head and neck surgery. There is some evidence to suggest a protective role of hypothyroidism with respect to disease control survival in head and neck and other cancers.

SUMMARY

Hypothyroidism is common after treatment of head and neck cancers. Thyroid function studies should be obtained prior to and at regular intervals after treatment. Prompt recognition and intervention may prevent or reverse adverse physiological outcomes. Further studies are necessary to evaluate the role of permissive hypothyroidism in the context of treated head and neck malignancies.

Primary and Central Hypothyroidism After Radiotherapy for Head-and-Neck Tumors

PURPOSE

To investigate the incidence of radiotherapy (RT)-induced central and primary hypothyroidism regarding total dose, fractionation, and adjuvant chemotherapy.

METHODS AND MATERIALS

We retrospectively reviewed the data from 312 patients treated with RT for extracranial head-and-neck tumors between 1964 and 2000. The cervical lymph nodes were irradiated in 197 patients. The radiation doses to the thyroid gland and hypothalamic-pituitary axis were estimated by reconstructing the treatment plans.

RESULTS

Clinical central hypothyroidism (CH) was observed in 17 patients (5.4%); the median clinical latency was 4.8 years. Clinical primary hypothyroidism (PH) was observed in 40 patients (20.3%); the median clinical latency was 3.1 years. Multivariate analysis of clinical CH revealed that fractionation, adjuvant chemotherapy, and total dose to the pituitary were not significant. Multivariate analysis of clinical PH revealed that the total dose to the thyroid (p = 0.043) was significant, but adjuvant chemotherapy, age, and gender were not. Of the patients tested for hypopituitarism, 14 (20.3%) of 69 demonstrated subclinical CH and 17 (27.4%) of 62 demonstrated subclinical PH. The 5-year and 10-year rates of freedom from clinical CH and PH were 97% and 87% and 68% and 67%, respectively. Of the patients tested, the 5-year and 10-year rates of freedom from subclinical CH and PH were 91% and 78% and 71% and 71%, respectively.

CONCLUSION

Clinical and subclinical manifestations of late radiation toxicity were observed in the thyroid and hypothalamic-pituitary axis. Although CH did not indicate a dependence on fractionation, adjuvant chemotherapy, or total dose to the pituitary, PH showed a dependence on the total dose to the thyroid gland.

A case of hypothyroid Graves' disease following external radiation therapy to the cervical region

A case of hypothyroid Graves' disease occurred following external radiation therapy to the cervical region is described. Severe hypothyroidism developed in a 56-year-old man 6 months after external radiation therapy for submandibular cancer. Serological evaluation of thyroid autoimmunity revealed the presence of antithyroid antibodies and thyrotropin-binding inhibitory immunogloblins (TBII). Diplopia, limitation of downward gaze, and palpebral edema developed 2 years after levothyroxine replacement therapy. Ocular magnetic resonance imaging revealed marked hypertrophy of the bilateral extraocular muscles with signal hyperintensity on T2-weighted images. This infiltrative ophthalmopathy showed marked improvement after additional treatment with high-dose methylprednisolone and orbital radiation, in parallel with a decrease in TBII. These results suggest that radiation-associated thyroidal injury might be associated with the etiology of hypothyroid Graves' disease.

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.

Acute radiation thyroiditis

PURPOSE

Radiation-induced thyroid dysfunction is considered a late effect. We prospectively assessed acute reactions of the thyroid to external neck irradiation.

METHODS AND MATERIALS

This study included 22 patients in whom the thyroid was incidentally exposed to therapeutic doses of radiation. Thyroid function tests included measurements of serum thyroid stimulating hormone (TSH), free and total triiodothyronine (T3) and thyroxine (T4), thyroglobulin, and antithyroid antibodies. These tests were performed before radiotherapy (baseline values), after approximately 40 Gy had been administrated, 2 weeks after the end of radiotherapy, and 3 and 6 months after the beginning of radiotherapy.

RESULTS

Mean serum levels of TSH were 1.53, 0.55, 0.78, 2.14, and 7.57 microU/ml before radiotherapy, after 40 Gy irradiation, 2 weeks after the end of radiotherapy, and 3 and 6 months after radiotherapy, respectively. Thus, levels of TSH exhibited two phases: a significant decrease during radiotherapy (thyrotoxic phase) and an increase after radiotherapy (hypothyroid phase) (baseline vs. 40 Gy: p < 0.0001, baseline vs. 6 months: p = 0.003). Increases of thyroid hormones were subtle during radiotherapy.

CONCLUSIONS

We believe that radiation promotes release of excessive amounts of thyroid hormones during radiotherapy owing to suppression of TSH secretion. In addition to the late damage (hypothyroidism), thyrotoxicosis occurs when the thyroid gland receives a therapeutic doses of external radiation.

Hypothyroidism in head and neck cancer patients: experimental and clinical observations

Damage to the thyroid gland may occur in patients undergoing treatment for head and neck neoplasms. This injury may result from damage incurred during surgery, from radiation therapy, or a combination of the two. Development of hypothyroidism is often insidious with potential harmful effects. An experimental study was performed to study the effects of hypothyroidism in pigs whose skin closely approximates that of the human. Wound tensile strength and flap necrosis were studied in the hypothyroid animal treated by surgery, radiation, and a combination of the two. The results of this study indicate that hypothyroidism alone has no significant unfavorable impact on wound tensile strengths or flap survival. When combined with preoperative radiation, however, there are statistically significant deleterious effects on both wound tensile strengths and flap survival. Histologically, collagen fibers within the wound appear shorter and thinner, which probably accounts for decreased wound tensile strengths. A clinical review of 62 head and neck cancer patients was also conducted. Within the study group, 10% of patients developed abnormally low thyroxine measurements, whereas 15% developed high thyroid-stimulating hormone levels as the only evidence of early primary hypothyroidism. Hypothyroidism was not statistically related to tumor size, nodal status, clinical staging, or treatment group (surgery alone, radiation alone, or combination surgery and radiation). A previously unreported finding is that patients who develop a second primary tumor are significantly at risk for developing hypothyroidism. All patients diagnosed with a head and neck cancer should undergo baseline thyroid function testing, including measurement of TSH, and have serial repeat testing after treatment. Thyroid function determination should be mandatory in patients undergoing oncologic salvage procedures or treatment of a second primary tumor.

Thyroid dysfunction after radiation therapy in head and neck cancer patients

INTRODUCTION

The reported incidence of hypothyroidism following surgery and/or radiation therapy for head and neck cancer varies widely. Most patients undergo thyroid lobectomy during laryngectomy. Standard radiation treatment portals often include the thyroid gland. The insidious development of hypothyroidism may be misdiagnosed. This study examines the incidence of thyroid dysfunction in the setting of head and neck cancer therapy.

MATERIALS AND METHODS

Thyroid function tests were performed on 100 consecutive patients treated in the head and neck tumor clinic. Statistical inferences on proportions were made using chi-square analysis.

RESULTS

Therapy included surgery only (10 patients), radiation therapy only (28 patients), and combined therapy (62 patients). These patients experienced thyroid dysfunction in 0%, 29%, and 45% of individuals respectively. These differences were statistically significant (P < .05). The highest rate of dysfunction (69%) was associated with patients undergoing laryngectomy and radiation therapy. When laryngectomy was not performed, thyroid dysfunction occurred in 28%.

CONCLUSION

The likelihood of thyroid dysfunction after radiation therapy is high particularly when combined with surgery in which thyroid lobectomy is performed and the contralateral lobe is potentially devascularized. These results suggest that radiation therapy is a primary factor in alteration of thyroid function. We recommend that routine thyroid function testing be part of follow-up of all head and neck cancer patients.

Hypothyroidism following radiotherapy for head and neck cancer: multivariate analysis of risk factors

The incidence of hypothyroidism following radiotherapy for head and neck cancer is 10-45% in several series. In order to identify possible risk factors a multivariate analysis was performed in 221 patients previously treated with either radiotherapy alone or combined with surgery or chemotherapy. Diagnostic procedures included: total T3 and T4, free T4 and TSH measured by radioimmunoassay, and thyroid scintigraphy. The absolute rate of hypothyroidism was 41.17% (subclinical 26.24%, clinical 14.93%). No thyroid nodules were detected in any patient. By multivariate analysis, risk factors that significantly influenced a higher incidence of hypofunction were: high radiation dose (p = 0.000), combination of radiotherapy and cervical surgery (p = 0.003), time from therapy (p = 0.022) and no shielding of midline (p = 0.026).

Hypothyroidism following combined treatment for hypopharyngeal and laryngeal carcinoma

The development of hypothyroidism following combined treatment for pharyngeal and laryngeal cancer has received little attention in the literature. We prospectively studied 32 patients over 4 years to determine the incidence of such hypothyroidism and to examine the effect of hemithyroidectomy associated with a combined treatment modality. All patients were men with pharyngeal or laryngeal squamous cell carcinomas and no prior history of thyroid disease. Treatment consisted of radical surgery (30 of 32 patients), followed by postoperative radiotherapy (31 patients). The results of thyroid function tests (free triiodothyronine, free thyroxine, and thyroid-stimulating hormone [TSH]) were all normal preoperatively; tests were repeated every 3 months after treatment. Elevation of TSH values in two successive blood samples was required to make a diagnosis of hypothyroidism. Of 12 patients who underwent hemithyroidectomy as part of total pharyngolaryngectomy and postoperative radiotherapy, 7 became hypothyroid a mean of 6 months after treatment. Twenty patients had similar combined treatment but without thyroid resection. Hypothyroidism developed a mean of 10 months after treatment in only four patients in this group (p less than 0.05). We conclude that hypothyroidism frequently develops following combined treatment for pharyngeal and laryngeal cancer even when thyroid resection has not been performed. Patients should be evaluated postoperatively and carefully monitored by means of serial thyroid function tests.

Thyroid-stimulating hormone levels after radiotherapy and combined therapy for head and neck cancer

Sixty-eight patients were studied prospectively with serial thyroid-stimulating hormone (TSH) levels after radiotherapy for head and neck neoplasms. Overall, 57% of the patients developed elevated TSH levels. Excluding patients with less than 2 years follow-up, 85% developed an elevated TSH. Ninety-two percent of patients treated with partial thyroidectomy and radiotherapy developed an elevated TSH. Most TSH elevations occurred within 1 year of treatment. The dose of radiotherapy used and the performance of hemithyroidectomy were related to the development of elevated TSH levels (p less than 0.05). The performance of radical neck dissection, gender, hyperfractionated radiotherapy and the use of chemotherapy were not related to the development of an elevated TSH (p greater than 0.05).

Thyroid diseases after treatment of Hodgkin's disease

BACKGROUND AND METHODS

Thyroid disease, especially hypothyroidism, is common in patients with Hodgkin's disease who have been treated with irradiation. We reviewed the records of 1787 patients (740 women and 1047 men) with Hodgkin's disease who were treated with radiation therapy alone (810 patients), radiation and chemotherapy (920 patients), or chemotherapy alone (57 patients) at Stanford University between 1961 and 1989. Among these patients, 1533 were alive at the last follow-up, and 254 had died of causes other than Hodgkin's disease. (Four other patients were excluded from the analysis because they had undergone thyroidectomy before treatment for Hodgkin's disease. The thyroid was irradiated in 1677 patients. Follow-up averaged 9.9 years.

RESULTS

A total of 573 patients had clinical or biochemical evidence of thyroid disease. Among the 1677 patients whose thyroid was irradiated, the actuarial risk of thyroid disease 20 years after treatment was 52 percent, and it was 67 percent at 26 years. Hypothyroidism was found in 513 patients. A total of 486 patients received thyroxine therapy for elevated serum thyrotropin concentrations and either low free thyroxine (208 patients) or normal free thyroxine values (278 patients); 27 had transient elevations of the serum thyrotropin level that were not treated. Graves' hyperthyroidism developed in 30 patients (2 of whom had not undergone thyroid irradiation), and ophthalmopathy developed in 17 of these patients. Ophthalmopathy developed in four other patients with Graves' disease during a period of hypothyroidism (n = 3) or euthyroidism (n = 1). The risk of Graves' disease was 7.2 to 20.4 times that for normal subjects. Silent thyroiditis with thyrotoxicosis developed in six patients. Forty-four patients were found to have single or multiple thyroid nodules, 26 of whom underwent thyroidectomy. Six of the 44 had papillary or follicular cancers. Among the patients who did not undergo operation, 12 had small functioning nodules, 4 had cysts, and 2 had multinodular goiters. The actuarial risk of thyroid cancer was 1.7 percent. The risk of thyroid cancer was 15.6 times the expected risk.

CONCLUSIONS

High risks of thyroid disease persist more than 25 years after patients have received radiation therapy for Hodgkin's disease, reinforcing the need for continued clinical and biochemical evaluation. Prolonged follow-up confirms an elevated risk of thyroid cancer and Graves' disease as well as hypothyroidism in these patients.

[Hypothyroid hypertrophic myopathy following mantle irradiation for Hodgkin's disease. A case]

The authors report a case of hypothyroid hypertrophic myopathy consecutive to mantle irradiation for Hodgkin's disease. A rise in TSH level is frequent after mantle irradiation and it justifies prolonged monitoring of these patients' thyroid function, in view of the risk of patent hypothyroidism and perhaps cancer. The patient's age, the pre-irradiation lymphography and the chemotherapy associated with radiotherapy are all factors that influence the incidence of thyroid dysfunction, but there is no agreement concerning their relative importance. Hypertrophic myopathies due to hypothyroidism are rare, and their dramatic clinical presentation contrasts with an almost normal muscle histology. Alterations of energy metabolism and changes in the properties of myosin induced by hormonal deficiency account for the muscular weakness of these patients. On the other hand, the mechanism of muscle hypertrophy remains controverted, the most probable theory being and increase in the number of myotubes. Following irradiation, notably for Hodgkin's disease, the frequency of hypothyroidism requires a regular and systematic laboratory follow-up. Replacement therapy must be instituted if the basal TSH level increases, even if the T4 level is normal.

Hypothyroidism following radiotherapy for head and neck cancer

Hypothyroidism is not commonly considered a complication of radiotherapy for head and neck cancer. A series of 96 patients treated with radiotherapy alone or combined with surgery for head and neck cancer was retrospectively studied. All patients had radiation ports that included the thyroid gland. Hypothyroidism after radiotherapy was documented in 26% of all patients. The majority of patients had subclinical hypothyroidism manifested by elevated thyroid-stimulating hormone (TSH) levels. The incidence of hypothyroidism dramatically increased to 65% when radiotherapy was combined with surgery that included a partial thyroidectomy. In addition, we report the unusual occurrence of massive head, neck, and hypopharyngeal edema caused by severe hypothyroidism in two patients. We advocate routine monitoring of head and neck cancer patients for hypothyroidism after radiotherapy involving the thyroid gland and recommend levothyroxine replacement therapy for subclinical hypothyroidism.

Thyroid function in survivors of cancer

Thyroid function was assessed in three selected groups of children who had survived cancer. Children in group 1 had received radiotherapy to the thyroid area, group 2 had radiotherapy to the thyroid area and adjuvant chemotherapy, and group 3 had chemotherapy with or without radiotherapy away from the thyroid area. There were 75 survivors and 63 (40 boys, 23 girls) were available for study. Eighteen (29%) were found to have thyroid dysfunction, and these included all those who had had lymphangiograms or received a radiation dose greater than 40 Gy to the thyroid area. Only nine of the 18 children were already known to have thyroid dysfunction, and only 15 of 44 children who had had irradiation to the thyroid area had had their thyroid function examined. This study shows that children who have received radiotherapy to the thyroid area should have their thyroid function assessed regularly. Chemotherapy does not appear to be a risk factor but longer follow up of these children is necessary.

Hyponatraemia and hypothyroidism in a previously irradiated case of carcinoma of the tongue

A case of squamous cell carcinoma of the tongue was complicated by post operative hyponatraemia. The criteria for the syndrome of inappropriate secretion of anti diuretic hormone, [ADH] (SIADH) were met but the patient remained hyponatraemic despite adequate treatment. The patient had previously received radical external radiotherapy to the neck and was found to be profoundly hypothyroid. Correction of the hypothyroid state led to clinical and biochemical recovery. The frequency of post-irradiation hypothyroidism and the possible mechanisms of hypothyroid-induced hyponatraemia are discussed.

Radiation-associated thyrotoxicosis

We studied 154 consecutive patients with a diagnosis of thyrotoxicosis seen at Roswell Park Memorial Institute from 1963 to 1982. The retrospective review of the clinical materials revealed that 23 (15%) had a previous history of therapeutic radiation for various diseases. The radiation dose ranged from several to 3600 rads to the thyroid with a mean latency of 14.2 +/- 3.0 years. In 11 out of 16 patients who were tested for antithyroglobulin and antimicrosomal showed positive titers of either or both antibodies (69%). In a small number of patients, thyroid stimulating immunoglobulins were studied; long-acting thyroid stimulators (LATS) were positive in one of six tested and thyrotrophin binding inhibitory immunoglobulins (TBII) in five of eight. The radiation-associated thyroidal dysfunction appears to be associated with the organ-specific autoimmune processes and could manifest as either hypo- or hyperfunction of the gland.

Solid malignancies in children and adolescents

The cure rate in childhood cancer has improved markedly during the past 20 years. In the 1960s the cure rate was about 20 to 30 per cent, but today more than 50 per cent of children and adolescents with cancer are being cured. This improvement is principally due to multidisciplinary teamwork in diagnosing, staging, and treating children with cancer; newer and more chemotherapeutic agents; and a recognition that combination therapy consisting of surgery, radiotherapy, and chemotherapy is frequently indicated.

Thyroxine administration during radiation therapy to the neck does not prevent subsequent thyroid dysfunction

In an attempt to reduce the incidence of hypothyroidism following irradiation of the neck, we administered oral L-thyroxine in doses sufficient to suppress serum TSH to 20 patients receiving radiation therapy for Hodgkin's disease or other lymphomas. L-thyroxine was discontinued when radiation therapy was completed. Twenty similar patients who did not receive L-thyroxine during radiation therapy served as a control group. After a mean follow-up period of 33 months, seven patients (35%) in the L-thyroxine group developed elevation of serum TSH and were started on chronic L-thyroxine therapy. In the control group, after mean follow-up of 19 months, five patients (25%) developed elevation of TSH and were started on chronic L-thyroxine. We conclude that suppression of serum TSH during neck irradiation does not prevent subsequent thyroid dysfunction.

Hypothyroidism

Hypothyroidism is a clinical entity first defined almost 100 years ago; it is caused, for the most part, by an autoimmune disorder or treatment of previous hyperthyroidism and so the vast majority have primary hypothyroidism. While the "textbook picture" does occur, the clinical findings in patients with mild to moderate disease are often nonspecific, particularly in the neonate and in the elderly. Diagnosis of primary hypothyroidism depends on showing that the serum TSH is elevated. Effective treatment, unchanged in principle since the 1890's, is best done with oral L-thyroxine. By using the serum TSH as well as the clinical findings as end-points, one can treat each patient individually.

Graves' disease with ophthalmopathy following radiotherapy for Hodgkin's disease

The number of patients achieving long-term survival following neck irradiation for Hodgkin's disease and other malignancies is increasing. Paralleling this increase in survivors is the development of late complications of the therapy itself. Eleven patients have previously been reported who developed Graves' ophthalmopathy 18 months to seven years after receiving neck radiotherapy for nonthyroidal malignancies. The seven patients who had HLA typing were all HLA-B8 negative, despite the reported association of the HLA-B8 antigen with Graves' disease. A patient who is HLA-B8 positive who developed Graves' ophthalmopathy and hyperthyroidism nine years after receiving mantle radiotherapy for Hodgkin's disease is reported. It is recommended that Graves' disease be included among the thyroid diseases that receive consideration during follow-up of patients who have received mantle radiotherapy.

Hypothalamic, pituitary and thyroid dysfunction after radiotherapy to the head and neck

One hundred-ten patients who had nasopharyngeal cancer and paranasal sinus tumors and were free of the primary disease were studied one to 26 years following radiotherapy. There were 70 males and 40 females ranging in age from 4 to 75 years, with a mean age of 36.5 years. During therapy both the hypothalamus and the anterior pituitary gland were in the field of irradiation. The radiation dose to the hypothalamus and the anterior pituitary gland was estimated to be 400 to 7500 rad with a median dose of 5618 rad to the anterior pituitary gland and a median dose of 5000 rad to the hypothalamus. We found evidence of endocrine deficiencies in 91 of the 110 patients studied. Seventy-six patients showed evidence of one or more hypothalamic lesions and 43 patients showed evidence of primary pituitary deficiency. Forty of the 66 patients who received radiotherapy to the neck for treatment or prevention of lymph node metastasis showed evidence of primary hypothyroidism. The range of the dose to the thyroid area was 3000 to 8800 rad with a median of 5000 rad. One young adult woman who developed galactorrhea and amenorrhea 2 years following radiotherapy showed a high serum prolactin level, but had normal anterior pituitary function and sella turcica. She regained her menses and had a normal pregnancy and delivery following bromocriptine therapy. These results indicate that endocrine deficiencies after radiotherapy for tumors of the head and neck are common and should be detected early and treated. Long-term follow-up of these patients is indicated since complications may appear after the completion of radiotherapy.

Thyroid dysfunction among long-term survivors of bone marrow transplantation

Thyroid function studies were followed serially in 27 long-term survivors (median 33 months) of bone marrow transplantation. There were 15 men and 12 women (median age 13 1/12 years, range 11/12 to 22 6/12 years). Aplastic anemia (14 patients) and acute nonlymphocytic leukemia (eight patients) were the major reasons for bone marrow transplantation. Pretransplant conditioning consisted of single-dose irradiation combined with high-dose, short-term chemotherapy in 23 patients, while four patients received a bone marrow transplantation without any radiation therapy. Thyroid dysfunction occurred in 10 of 23 (43 percent) irradiated patients; compensated hypothyroidism (elevated thyroid-stimulating hormone levels only) developed in eight subjects, and two patients had primary thyroid failure (elevated thyroid-stimulating hormone levels and low T4 index). The abnormal thyroid studies were detected a median of 13 months after bone marrow transplantation. The four subjects who underwent transplantation without radiation therapy have remained euthyroid (median follow-up two years). The only variable that appeared to correlate with the subsequent development of impaired thyroid function was the type of graft-versus-host disease prophylaxis employed; the irradiated subjects treated with methotrexate alone had a higher incidence of thyroid dysfunction compared to those treated with methotrexate combined with antithymocyte globulin and prednisone (eight of 12 versus two of 11, p less than 0.05). The high incidence and subtle nature of impaired thyroid function following single-dose irradiation for bone marrow transplantation are discussed.

Hypothyroidism following treatment for head and neck cancer

One hundred ninety-six head and neck patients were studied to determine the effects of radiation therapy and surgery on thyroid function. Serum thyroid-stimulating hormone (TSH) levels were obtained as a screening test for primary hypothyroidism. Elevated TSH levels were found in 57 of the 196 patients (29.1%). The highest incidence of abnormal TSH values (66%) occurred in the group treated with combination radiation therapy and surgery, including partial thyroidectomy. TSH levels rose early in the posttreatment period with 60% of the abnormal values occurring within the first three posttreatment years. Posttreatment thyroid dysfunction was twice as common in women (48.6%) as in men (25.4%). When serum thyroxine levels by radioimmunoassay (T4RIA) were correlated with the elevated serum TSH levels, a similar pattern was seen with 65% of the patients in Group 3 having a decreased T4RIA level indicating overt hypothyroidism. Pretreatment levels of thyroid function including thyroid antibody studies should be established for all patients. Serial TSH levels should be done every three months during the first three posttreatment years and semiannually thereafter as long as the patient will return for follow-up care. All patients treated with combination radiation therapy and surgery who develop elevated TSH levels should be treated with thyroid replacement therapy. Patients receiving radiation therapy alone should receive replacement thyroid therapy if they develop a depressed T4RIA value or a pattern of gradually increasing TSH levels.

Thyroid abnormalities associated with treatment of malignant lymphoma

The effects on the thyroid of radiation therapy to the neck and/or chemotherapy were investigated in 54 Hodgkin's and 72 non-Hodgkin's lymphoma patients. These patients had received radiation therapy with doses ranging from 2000 to 4000 rad (median 3600 rad) to the cervical or mantle fields and/or multiple-agent chemotherapy following usual staging procedures. Palpable abnormalities of the thyroid were found in 15 patients. The patients with irradiation to the neck had a higher incidence of hypothyroidism than those patients treated with chemotherapy alone (31/74 vs. 8/52, P less than 0.001 for TSH and 10/74 vs. 1/52, P less than 0.025 for T4). A higher frequency of elevated serum TSH levels and antithyroid antibodies were also observed in patients receiving radiation therapy alone to the neck than in those receiving both radiation therapy and chemotherapy (19/33 vs. 12/41, P less than 0.025 for TSH and 16/33 vs. 7/41, p less than 0.01 for antibodies), suggesting that chemotherapy agents may reduce the thyroid dysfunction induced by irradiation. There was no difference in prevalence of elevated TSH levels following irradiation to the neck between patients in whom lymphangiogram was or was not performed (21/51 vs. 10/23).

Environmental factors altering thyroid function and their assessment

Chronic ingestion of modest doses of dietary iodine, radiation, and polyhalogenated biphenyls (PCB's and PBB's) are environmental factors with known or suspected adverse effects on the human thyroid. Iodine consumption in the United States is approaching 1 mg daily for a large segment of the population. Data are reviewed which support the need for concern regarding the long-term adverse effects of dietary iodine on thyroid function, particularly in certain susceptible individuals. Environmental sources of radiation pose a significant risk of thyroid cancer and hypothyroidism under certain circumstances which may be intentional, inadvertent, or accidental. Exposure to polyhalogenated biphenyls during manufacture or as industrial pollutants are hazardous to man and to wildlife in moderate or large quantities and perhaps also in small amounts. The need to investigate the potential harm posed by these factors in the quantities commonly encountered is emphasized.

Disorders of endocrine function following cancer therapies

There is a growing body of literature detailing the endocrine consequences of cancer therapy. Certain conclusions can be drawn from the data presented. Patients who have received incidental hypothalamic--pituitary gland irradiation need to be followed carefully with serial dynamic hormonal evaluations, as they are at high risk of developing growth hormone and prolactin abnormalities and can develop other pituitary tropic hormone deficiencies as well. Children especially should be monitored closely as GH deficiency can be corrected if detected early. Patients who have received radiation to the head and neck region will need long-term (up to 30 years) surveillance for the development of thyroid cancer, hyperparathyroidism or hypothyroidism. Persistent elevations of TSH after incidental thyroidal irradiation are frequently seen and should be reversed with thyroid hormone administration in an attempt to minimize TSH stimulation of the irradiated gland. Radiation to the gonads will cause graded damage dependent on the dose delivered and the mode of fractionation. Age in a woman seems to be a significant factor of radiation sensitivity. Certain chemotherapeutic agents are radiomimetic in their gonadal effects; to date the alkylating agents have been most commonly implicated. FSH elevations herald gonadal damage (aspermia or loss of follicles) and should be looked for in patients receiving abdominal radiation or systemic chemotherapy. Leydig cell dysfunction occurs less frequently. Of all the iatrogenic endocrine complications discussed, some are eminently treatable, and some are quite preventable. Greater awareness of the unexpectedly high incidence of hormonal dysfunction can help lessen therapy-induced morbidity in long-term cancer survivors.

Thyroid carcinoma after high-dose external radiotherapy for Hodgkin's disease: report of three cases

Three patients (two female and one male), who had received mantle irradiation for Hodgkin's disease eight, ten, and twelve years previously, developed papillary thyroid carcinoma. The radiation doses to the necks overlying the site of thyroid cancers were 3000, 4000, and 4100 rads, respectively. It has been stated that there is no risk of developing thyroid cancer with such high doses of external irradiation but apparently this complication will be encountered in a small number of patients.

Myxedema coma and inappropriate antidiuretic hormone secretion after deep neck irradiation: clinical implications and report of a case

A case report is presented in which myxedema coma and inappropriate antidiuretic hormone secretion developed as a result of radiation therapy and surgery to the neck area in a patient with recurrent metastatic squamous cell carcinoma of the floor of the mouth. Laboratory findings of low thyroxine level and the findings of persistent hyponatremia and hypoosmolality of serum in spite of persistent sodium loss in the urine were helpful in diagnosing the problem. Treatment included thyroid hormone replacement and fluid restriction resulting in complete reversal of her condition. We believe that patients with head and neck cancer who have undergone a course of radiation to the neck, and particularly when thyroid function might have been altered by previous subtotal thyroidectomy as part of a curative resection, should be carefully followed with periodic thyroid function assays and serum electrolytes with particular attention to serum sodium values.

Ionizing irradiation and the induction of clinically significant disease in the human thyroid gland

Because of increasing concern over continuing medical and potential nonmedical exposure of the thyroid to radiation, risk estimates have been developed for acute thyroiditis, hypothyroidism, and both benign and malignant thyroid nodules following exposure of the human thyroid to external and internal sources of ionizing radiation. These estimates are unique in that they are based entirely on data in human subjects are included corrections for the spontaneous occurrence of thyroid disease in human populations not subjected to radiation whenever possible.

Thyroid dysfunction following external irradiation to the neck for Hodgkin's disease in childhood

Thyroid function was studied in 32 patients who had received neck irradiation during childhood for Hodgkin's disease. All except one patient received a dose of 2500-3000 rad over a period of 19-25 days. In 12 patients lymphangiography was performed. Clinically all patients were considered euthyroid. One had a thyroid swelling which was cystic in nature. Five (16%) patients were biochemically hypothyroid, 17 (53%) were euthyroid with an elevated basal serum TSH concentration and a further seven (22%) were euthyroid with a normal basal serum TSH level but an augmented thyroid-stimulating hormone (TSH) response to thyrotrophin-releasing hormone (TRH). Only three (9%) patients had completely normal thyroid function tests. The basal serum TSH concentration and the peak serum TSH response to TRH were significantly greater in the patients who received neck irradiation and lymphangiography than in those who received neck irradiation alone. In addition the free thyroxine index decreased significantly as the time interval between treatment and study increased in the lymphangiography group. These data demonstrate that the normal thyroid gland is vulnerable to the damaging effects of external irradiation, and that the combination of neck irradiation and lymphangiography is more likely to result in thyroid dysfunction than is neck irradiation alone. Furthermore, in view of the deterioration in thyroid function with time, periodic clinical and biochemical assessment of thyroid function is clearly indicated.

Long-term effects on external radiation on the pituitary and thyroid glands

Chronic damage following external irradiation of the normal pituitary and thyroid glands, delivered incidentally during radiotherapy of neoplasms of the head and neck may be more common than has been appreciated in the past. A case of a child who developed pituitary dwarfism 5 1/2 years after radiation therapy has been delivered for an embryonal rhabdomyosarcoma of the naso-pharynx is described. A review of similar cases from the literature is presented. Likewise, external irradiation of the normal thyroid gland produces a spectrum of radiation-induced syndromes. Clinical damage to the pituitary and thyroid glands is usually manifested months to years after treatment and is preceded by a long subclinical phase. A careful exclusion of these glands from radiation treatment fields is recommended whenever possible. An early detection of endocrine function abnormalities in patients receiving radiation to these glands is desirable, since appropriate treatment may prevent the deleterious effects of external irradiation of the pituitary and thyroid glands.