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

Serum thyroglobulin after mantle irradiation for Hodgkin's disease

Thyroid function and serum thyroglobulin levels were studied in 66 subjects whose Hodgkin's disease had been previously treated by cervical, mediastinal and axillary lymph node (mantle) irradiation. Three patients were already undergoing treatment for thyroid disorders (one for primary hypothyroidism, two for Graves' disease) and a fourth was found to have euthyroid Graves' disease. 36 (Group I) of the remaining 62 patients had normal free thyroxine indices, normal basal thyrotrophin (TSH) levels and normal TSH response to thyrotrophin releasing factor (TRH). In 20 patients (Group II) free thyroxine indices were normal but either basal TSH levels were raised or normal basal TSH levels were associated with an exaggerated response to TRH. In 6 patients (Group III) free thyroxine indices were subnormal. Although results of thyroid function tests in group I lay within the normal range, the mean free thyroxine index was significantly lower and mean basal and peak TSH levels were significantly higher than those of a group of 35 normal subjects, indicating mild thyroid hypofunction. Elevated thyroglobulin levels were demonstrated in 11 irradiated subjects (18%). Mean thyroglobulin levels were significantly raised in each of the three groups of irradiated subjects. Significant positive correlations were found between log serum thyroglobulin and log basal TSH (r = 0.453, P less than 0.001) and log peak TSH (r = 0.515, P less than 0.001) levels. Mild thyroid hypofunction is common after mantle irradiation for Hodgkin's disease and raised serum thyroglobulin levels are a sensitive indicator of TSH stimulation of the damaged thyroid gland.

Thyroid carcinoma and acute lymphoblastic leukemia in childhood

A 12-year-old boy with T-cell ALL was found to have occult papillary thyroid carcinoma at autopsy. This patient was treated with chemotherapy but no radiotherapy was utilized. Family history was not contributory. Because of short latent period (14 months) and no history of radiotherapy, an intrinsic factor might have played a major role in developing this second malignancy. Currently 11 solid tumors have been reported as second malignant neoplasms after ALL in childhood. Four (including this case) of 11 were thyroid carcinoma. Two of them did not receive any radiotherapy. Special interrelation between ALL and thyroid carcinoma may be considered. And this interrelation should be taken into account in following the patients with ALL in the future.

Risk factors for thyroid abnormalities after neck irradiation for childhood cancer

Thyroid evaluations were performed in 95 patients who received radiotherapy to the neck region for childhood cancer five to 34 years earlier. Fifty-six patients (61 percent) had at least one abnormality of serum free thyroxine index, serum thyroid-stimulating hormone (thyrotropin), or thyroid palpation. Seven had subnormal free thyroxine index and 40 had elevated thyrotropin concentrations. Thyroidal radiation doses of 3,000 or more rads and lymphangiography independently increased the risk (p less than or equal to 0.01) of an elevated serum thyrotropin concentration (present in 11 percent of patients with neither risk factor, 50 percent of those who underwent lymphangiography and received less than 3,000 rads, 46 percent of those who had 3,000 or more rads and no lymphangiography, and 76 percent of those with both), but duration of follow-up did not. Twenty-six patients had thyroid nodules and six others had diffuse thyroid enlargement. The frequency of palpable abnormalities increased with the follow-up time after radiation (30 percent of patients followed up less than 10 years had abnormalities versus 43 percent of those followed up 10 or more years, p = 0.03), but was not related to the serum thyrotropin level, radiation dose, or lymphangiography. Among 10 patients who had surgery for nodules, three had localized papillary thyroid carcinomas.

Multifocal follicular carcinoma of thyroid following radiotherapy for Hodgkin's disease

A 21-year-old white male developed multifocal follicular carcinoma of the thyroid gland 17 years after receiving neck irradiation (3000 rad) for Hodgkin's disease. The tumour was unique in that follicular carcinoma has not previously been reported as having a multifocal origin, even after high dose radiotherapy.

The "free" routine postcatheterization urogram: a cost/benefit analysis

Postangiography urography has become routine procedure in most centers performing cardiac catheterization in children. We analyzed the x-radiation dosage and clinical yield of this procedure. Using lithium fluoride thermoluminescent dosimeters, radiation exposure to the abdomen and gonads was measured in 35 children during postangiography urography. Results of 334 consecutive routine postangiography cine-urograms were evaluated based on clinical significance and compared to previous reports on this subject. Average absorbed abdominal radiation dosage was 241 mR +/- 240 from cine-urography, 16 mR +/- 13 from fluoroscopy, and 107 mR +/- 111 from a single abdominal roentgenogram. Gonadal dosage averaged 8 mR and was uniformly less than 27 mR. Of 334 routine postangiography cineurograms, 282 (84%) were normal, 30 (9%) were technically inadequate, 12 (3%) had abnormalities that were clinically insignificant or were falsely "positive" and in 10 (3%), clinically significant urologic conditions were confirmed. Because of the low yield of clinically significant anomalies and the added radiation exposure, we no longer perform routine postangiography cine-urography in children. Following cardiac angiography, the upper renal collecting systems are examined fluoroscopically. If abnormalities are suspected or fluoroscopy is equivocal, a single abdominal roentgenogram is performed. Using this procedure, mean average absorbed abdominal radiation dose can be reduced from 241 mR to 30.5 mR.

Primary hypothyroidism as a complication after treatment of tumours of the head and neck

In 100 successive patients treated for tumour in the head and neck region, the function of the thyroid gland was evaluated during follow-up by determination of the serum levels of thyroid stimulating hormone and thyroxine. Radiation therapy alone did not lead to hypothyroidism, 4 patients had no dysfunction after laryngectomy for recurrent tumour after irradiation. Ten of 17 (59%) patients treated with irradiation and surgery including hemithyroidectomy and with a follow-up period of more than one year developed functional disturbance; in the absence of hemithyroidectomy one of 10. In patients who underwent hemithyroidectomy and developed hypothyroidism, the interval between surgery and postoperative irradiation was shorter than in those who did not develop functional disturbance (31 versus 49 days).

Head and neck neoplasia following irradiation for benign conditions

A retrospective review of 143 patients with head or neck tumors who had received radiation therapy in the head and neck area for benign conditions during childhood or adolescence was conducted. This included an analysis of 1,080 patients from the Evanston Hospital Irradiated Thyroid Evaluation Clinic, which was established to define the relationship between irradiation and the subsequent development of thyroid neoplasia. The data support the following concepts of irradiation-induced neoplasia: (1) The thyroid, parathyroid, and salivary glands can develop benign and malignant changes after irradiation for benign conditions, with latent periods averaging about 30 years; (2) Once a glandular abnormality within the irradiated field appears, the risk of other glands in the field developing neoplastic changes is significantly increased.

Radiation exposure to the child during cardiac catheterization

Few data are available regarding radiation exposure to children during cardiac catheterization. Using lithium fluoride thermoluminescent dosimeters, radiation exposure was measured during precatheterization chest roentgenography, fluoroscopy (hemodynamic assessment phase of catheterization) and cineangiography in 30 infants and children, ages 3 days to 21 years. Dosimeters were placed over the eyes, thyroid, anterior chest, posterior chest, anterior abdomen, posterior abdomen and gonads. Average absorbed chest doses were 24.5 mR during chest roentgenography, 5810 mR during catheterization fluoroscopy and 1592 mR during cineangiography. During the complete catheterization, average doses were 26 mR to the eyes, 431 mR to the thyroid area, 150 mR to the abdomen and 11 mR to the gonads. Radiation exposure during pediatric cardiac catheterization is low to the eyes and gonads but high to the chest and thyroid area. To decrease radiation dosage we suggest (1) low pulse-rate fluoroscopy; (2) substitution of contrast echocardiography for cineangiography; (3) large-plate abdominal/gonadal shielding; (4) a selective shield for thyroid area; (5) a very small field during catheter manipulation. Minimum radiation consistent with accurate diagnosis is optimal; however, erroneous or incomplete diagnosis is more dangerous than radiation-related hazards.

Solitary thyroid nodule. 2. Selective approach to management

Ordinarily, the history and physical examination and routine tests, including thyroid function tests, iodine 123 or technetium Tc 99m scans, and echography, will determine the best therapeutic approach to a solitary thyroid nodule. In the case of an asymptomatic, hypofunctional solid nodule, thyroid hormone suppression and fine-needle aspiration biopsy may be necessary to further delineate the best therapy.

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.

Management of thyroid nodules. I: History and physical examination, blood tests, X-ray tests, and ultrasonography

The approach to the management of the thyroid nodule remains controversial. Confusion exists because virtually any thyroidal disease can present as a clinically solitary nodule which means there is no uniformity regarding natural history, incidence, prevalence, epidemiology, and pathophysiology.. The variety of definitions of thyroid nodules and thyroid carcinoma and the different modes of study selection and individual bias add to the confusion. Diagnostic approaches have not yielded a completely reliable technique to differentiate benign from malignant thyroidal disease. A history of neck irradiation of cervical lymphadenopathy significantly increases the chance of thyroid malignancy, but other parameters of the history or physical examination as well as blood tests are unreliable. Ultrasound displays anatomic but not histologic features. X-ray techniques (plain films, computed tomographic scans, xeroradiography, chest x-ray, barium swallow, lymphography, and angiography) have been used to visualize thyroid nodules, with some techniques proving more useful than others.

Thyroid carcinoma following treatment for acute lymphoblastic leukemia

A 2 1/2-year-old girl with acute lymphoblastic leukemia received chemotherapy and prophylactic cranial irradiation. After six years of remission, including three years off therapy, metastatic thyroid carcinoma appeared in the cervical lymph nodes. The predisposing factors for the development of thyroid carcinoma as a second malignancy in this case are discussed. It is suggested that thyroid carcinoma should be added to the growing list of second malignancies in acute lymphoblastic leukemia and that careful thyroid examination be included in the follow-up of long-term survivors.

Malignant thyroid tumors after iodine-131 therapy: a retrospective cohort study

We studied the incidence of malignant thyroid tumors after 131I therapy in 2727 patients with hyperthyroidism and in 273 euthyroid patients with cardiac disease. The patients were all adults, with a mean age of 57 years. The 131I therapy was given between 1951 and 1965. The mean follow-up period was 13 years for the hyperthyroid patients (15 years for the 85 per cent surviving for more than five years) and six years for the cardiac patients (12 years for the 41 per cent surviving for more than five years). The incidence of malignant thyroid tumors was based on a search of the Swedish Cancer Registry for the occurrence of such tumors in any of the 3000 patients. At present there is no increased incidence of malignant thyroid tumors after 131I therapy (four cases observed versus 3.2 cases expected).

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.

The early follow-up of 131I-treatment of thyrotoxicosis

No general agreement exists concerning the optimal time for the first control of patients treated with 131I for thyrotoxicosis. Ten consecutive cases were followed clinically, and current laboratory thyroid tests were frequntly performed during a 14 week period to point out the optimal control time and the best setup of control parameters for such patients. It is concluded that clinical examination, supplied with T4, T3, T3-test, and TSH determinations 12--14 weeks after therapy seems rational as a first step in the lifelong follow-up of these patients.

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.

Anaplastic carcinoma of the thyroid following external irradiation

Two patients with anaplastic carcinoma of the thyroid following irradiation for Hodgkin's disease are presented, and the previously reported cases briefly reviewed. The risk of late development of thyroid carcinoma is life-long and high-dose irradiation in patients with prolonged life expectancy may result in anaplastic carcinoma as well as less malignant histological forms.

Radiotherapeutic agents: properties, dosimetry, and radiobiologic considerations

Radioactive nuclides for treatment have occupied an important but somewhat diminishing role in the total practice of nuclear medicine. Although theoretically they should have important potentialities, particularly in the treatment of various forms of cancer, their development in this field has not kept pace with the progress in other treatment modalities in radiation oncology. Indications for the selection of appropriate isotopes for therapy revolve about the emission of beta particles of sufficient energy, which are administered in a chemical form that reaches the tumor. Methods of calculation of doses delivered to sites of deposition are discussed in the text. Radiobiologic considerations include the possibility of early deleterious effects from overdosage, and consideration of chromosomal changes of circulating lymphocytes and their implications. Late effects that have been of great public concern are confined almost solely to possible carcinogenesis, and this effect has been minimal in patients receiving therapeutic levels of radioactive drugs. Genetic and developmental effects, also, have been negligible. Complications encountered more frequently have been leukemia after extensive therapy of thyroid carcinoma, and local fibrosis after direct injection of radioactive colloids into tumor tissue.

Anaplastic cardcinoma of the thyroid in a population irradiated for Hodgkin Disease, 1910--1960

Post-irradiation carcinoma of the thyroid is usually histologically well-differentiated. In general, those subjects who developed carcinoma had been exposed to low-to-moderate doses of irradiation for benign conditions. We reviewed the charts of 520 patients with Hodgkin's disease seen at Roswell Park Memorial Institute, and found 2 cases of anaplastic carcinoma amongst other thyroidal abnormalities. The existing reports of post-irradiation carcinoma are reviewed and suggestions are made for the management of heavily irradiated, potentially cured patients with Hodgkin's disease.