Thyroid carcinoma after irradiation. Characteristics and treatment

Characteristics of follicular tumors and nonneoplastic thyroid lesions in children and adolescents exposed to radiation as a result of the Chernobyl disaster

BACKGROUND

In addition to the previously reported increase in incidence of thyroid carcinomas in Belarussian children after the Chernobyl disaster in April, 1986, benign thyroid lesions were also found to be increased in the exposed population.

METHODS

A total of 60 follicular neoplasms and benign nonneoplastic thyroid lesions arising after the Chernobyl disaster in children and adolescents of 7 to 18 years of age were studied.

RESULTS

The primary diagnoses in this series were follicular carcinoma in 1 (2%) case, follicular adenoma in 9 (15%), cystic adenomatoid nodule with papillae in 18 (30%), multinodular goiter in 18 (30%), diffuse hyperplasia in 2 (3%), diffuse hyperplasia with atypia and nodularity in 5 (8%), lymphocytic thyroiditis in 6 (10%), and thyroid cyst in 1 patient (2%). Additional histologic changes in thyroid glands from these patients were similar to those reported after radiation exposure, and included perifollicular fibrosis (72%), focal epithelial hyperplasia (73%), colloid accumulation (47%), follicular atrophy (33%), and cellular atypia (25%). Vascular abnormalities were found more often (75%) than previously reported in the thyroid gland after irradiation, and had a somewhat different appearance. They affected primarily medium-size arteries and were characterized by damage of the internal elastic lamina in addition to intimal fibrosis.

CONCLUSIONS

The first case of thyroid follicular carcinoma in the exposed Belarussian children was diagnosed after a latent period of 6.5 years, as compared with 4 years of minimal latency for post-Chernobyl papillary carcinomas. Among benign thyroid lesions, cystic adenomatoid nodules of papillary type and diffuse hyperplasia with cellular atypia and nodularity seem to be commonly associated with radiation exposure to the thyroid gland.

Pediatric thyroid cancer after the Chernobyl disaster. Pathomorphologic study of 84 cases (1991-1992) from the Republic of Belarus

BACKGROUND

During the initial period after the Chernobyl accident, large amounts of radioactive iodine were released in fallout, resulting in serious exposure to the thyroid gland in the residents of areas around the nuclear power station. Beginning in 1990, a definite increase in the incidence of thyroid cancer was noted in children of the Republic of Belarus.

METHODS

Morphologic and clinical features of 84 cases of post-Chernobyl thyroid carcinoma in Belarussian children from 5 to 14 years of age are reported. The latent period for tumor development was 4-6 years, with a mean of 5.8 years.

RESULTS

Papillary carcinoma was found in 83 patients and medullary carcinoma in one. Besides typical papillary carcinoma (14%), solid (34%), follicular (33%), mixed (10%), and diffuse sclerosing (9%) variants were observed. The follow-up period ranged from 8 months to 2.5 years. One patient died, local recurrence developed in 2, and cervical lymph node metastases developed in 10. To date, the incidence of local recurrence or metastatic disease after surgery was significantly higher in patients 5-8 years of age and in residents of areas nearest to the Chernobyl station.

CONCLUSIONS

Post-Chernobyl pediatric thyroid carcinoma is characterized by a short latency, a higher proportion of tumors arising in young children, and an almost equal sex ratio. Microscopically, these tumors were usually aggressive, often demonstrating intraglandular tumor dissemination (92%), thyroid capsular and adjacent soft tissue invasion (89%), and cervical lymph node metastases (88%). Papillary carcinoma was diagnosed in 99% of cases, with an unusually high frequency of solid growth patterns. Morphologic changes in nonneoplastic thyroid tissue were present in 90% of the glands, and the most specific findings were vascular changes and perifollicular fibrosis.

Papillary adenocarcinoma in thyroid hemiagenesis

Variation in the gross anatomy of the thyroid gland is relatively common. Although thyroid hemiagenesis is felt to be a rare anomaly, its incidence is probably underestimated as the diagnosis is usually incidental. The case of a 41-year-old woman with right thyroid hemiagenesis associated with papillary adenocarcinoma is presented. The diagnosis of hemiagenesis was established by isotope imaging and surgical exploration for a benign nodule. Seven years later she was seen with a recurrent neck mass, and an isotope scan revealed it to be a cold thyroid nodule. As she was diagnosed to have papillary adenocarcinoma, total thyroid lobectomy was performed and at present she remains disease-free.

Radiation induced thyroid neoplasms 1920 to 1987: a vanishing problem?

Radiation for benign diseases has been implicated as an etiologic factor in thyroid cancer. From 1930-60, over 2 million children may have been exposed to therapeutic radiation and it is estimated that up to 7% may develop thyroid cancer after a 5-40 year latency. Thyroid stimulating hormone, secondary to radio-induced hypothyroidism, has been implicated as causative in animals. Such data has led to expensive screening programs in high risk patients. Because of a decline in irradiation for benign diseases in children over the last 2 decades, we questioned whether the incidence of radiation induced thyroid neoplasms (RITN) was also decreasing. Twenty-six of 227 patients (11%) with thyroid malignancies seen at our institution from 1974-87 had a history of previous head and neck irradiation. These included 13 papillary, 3 follicular, and 7 mixed carcinomas as well as 2 lymphomas and 1 synovial cell sarcoma. None of these 26 patients had abnormal thyroid function tests at presentation. Mean latency from irradiation to the diagnosis of thyroid cancer was 25.4 years (6-55 year range). Compared to the reported increasing incidence of RITN from 1940-70, there appears to be a significant decrease since 1970. Based on our analysis, the use of expensive screening programs in high risk populations may no longer be warranted. Additionally, the routine use of thyroid replacement in previously irradiated chemically hypothyroid patients is not recommended.

Total thyroidectomy in irradiated patients. A twenty-year experience in 206 patients

During a period of 20 years (1965-1985), 206 consecutive patients were operated on for radiation-associated nodular thyroids. The ages ranged between 8 and 76 years (mean 38.7). there were 136 women and 70 men. The average duration between radiation exposure and operation was 27 years. The operations performed were total thyroidectomy (192) or, in patients who had undergone a previous lobectomy in another institution, another lobectomy (14). In addition, 25 patients required a neck dissection for nodal metastases and 27 underwent simultaneous subtotal parathyroidectomy for coexistent hyperparathyroidism. The pathologic findings were: 87 (42.2%) carcinoma (73 papillary, 13 follicular, 1 undifferentiated); 92 (44.7%) follicular adenomas; and 27 (13.1%) thyroiditis. To date, with an average follow-up of 6 years (0.5-31 years), only two patients have expired from recurrent disease. A third died of unrelated cause. A comparison of the first 100 patients (12 years) with the last 106 patients (8 years) demonstrated that the incidence of carcinoma has dropped from 48 to 37%, the incidence of lymph node metastases has decreased from 35 to 26%, and the incidence of bilaterality has fallen from 75 to 54%. On the basis of this series, it was concluded that total thyroidectomy is still indicated for radiation-associated nodular thyroids. However, if the trend of decreasing incidence, bilaterality, and metastatic disease persists, this approach may have to be reevaluated in the near future.

Radiation and thyroid carcinoma: radiotherapy, head and neck regions, thyroid carcinoma

Radiotherapy for benign conditions of the head and neck area was first linked to thyroid carcinoma in 1950. All the salivary glands, the parathyroids, and the facial skin can also develop neoplastic lesions in this setting. Thyroid carcinoma is most commonly papillary or mixed papillary and follicular. It is very often multifocal and can be detected by hand palpation, nuclear scanning, high resolution sonography, and needle aspiration. Each test has its limitations and appropriate protocols for screening and detection should be adapted to different medical centers. The surgical management is controversial and ranges from simple lobectomy to total thyroidectomy with adjuvant 131I treatment and thyroid suppression. We prefer total thyroidectomy if it can be performed safely. With adequate treatment the survival should be good. Prevention by administration of iodine at the time of exposure to radiation seems feasible and deserves further clinical trial.

Papillary carcinoma of the thyroid in two brothers after chest fluoroscopy in childhood

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Patterns of human thyroid parenchymal reaction following low-dose childhood irradiation

Microscopic changes in the thyroids of 68 patients who had received low-dose childhood irradiation to the head and neck and who presented with palpable thyroid abnormalities culminating in surgery are compared to 34 control thyroids obtained from age- and sex-matched autopsy cases. Eighty-eight percent of irradiated thyroids showed moderate to severe focal hyperplasia, 51% contained single or multiple adenomas or adenomatous hyperplastic nodules, 68% exhibited chronic lymphocytic thyroiditis, 51% revealed colloid nodules, 42% presented with oxyphile change, 25% had mild fibrosis and 59% contained well-differentiated papillary, follicular or mixed thyroid carcinoma averaging 1.6 cm in diameter. Three small carcinomas were of the sclerosing type. The non irradiated thyroids showed 32% colloid nodule formation, 17% focal hyperplasia, 6% adenomatous hyperplasia and no identifiable carcinomas. Several nonspecific histologic abnormalities are now recognized as following low-dose radiation to the thyroid, the most important being focal hyperplasia, which may represent a pre-malignant change in thyroid parenchyma.

Thyroid carcinoma induced by irradiation for Hodgkin's disease. Report of a case

In a 22-year-old male, who had been irradiated 16 years previously for Hodgkin's disease, a radiation-induced thyroid carcinoma developed. This was the only case with such development in a group of 207 cases with Hodgkin's disease who were treated by irradiation including the thyroid gland.

Changing clinical, pathologic, therapeutic, and survival patterns in differentiated thyroid carcinoma

Records of 792 patients with differentiated thyroid carcinoma seen at the Lahey Clinic Foundation over a 40-year period were analyzed; 631 patients had a minimum followup period of 15 years. Differentiated types currently constitute nearly 90% of thyroid carcinomas. The clinical presentation has improved substantially through the years, and the results of treatment generally have improved. The per cent of patients with primarily incurable and locally unresectable disease or distant metastases has decreased from 7% before 1950 to 1% currently, and this group resulted in almost one third of the total fatalities and one half of fatalities within the first 5 years after treatment. Clear relationships were demonstrated between older age, men, extraglandular extension, blood vessel invasion, major capsular involvement, multifocal disease, and higher mortality rates. Lymph node metastases were found to exert a protective effect in all categories of disease analyzed, and this effect was directly related to the number of lymph node metastases present such that no deaths occurred in those patients who had more than 10 node metastases. Surgical treatment recommended is subtotal thyroidectomy for patients at high risk of death from disease as defined by combinations of age, sex, and extraglandular extension. Patients at low risk or with small carcinomas can be treated satisfactorily by lobectomy. Lymph node resections should be of a limited type or a modified neck dissection and should be performed only therapeutically. No improvement, as judged by mortality or recurrence rates, could be demonstrated by the use of radio therapy after surgery, and its use should be discouraged. Thyroid hormone administered for suppression of endogenous thyroid-stimulating hormone production improved mortality rates significantly in patients with papillary and mixed forms of carcinoma in all age groups but did not affect survival in patients with follicular carcinoma of the thyroid.20

Adverse reactions to radiopharmaceuticals

This review covers the side effects and adverse reactions to radiopharmaceuticals that were reported in the literature over the past 25 years. The information published prior to 1970 is sporadic, but due to the increased utilization of nuclear medicine procedures and the recognition that radiopharmaceuticals may have pharmacologic side effects, a registry has existed since 1971 to tabulate information on such effects. This survey is medical, rather than pharmaceutical in emphasis and so the adverse reactions are classified according to the target-organ systems involved rather than according to the specific radionuclides or to pharmaceuticals. If any of the radiopharmaceuticals of present or past use are not mentioned in this review, it is because no reports on their side effects were retrived by us. Hopefully, the organized registry system suggested by the Society of Nuclear Medicine (SNM) will enable a more complete recording of side effects from radiopharmaceuticals in the future.

Thyroid cancer occurring as a late consequence of head-and-neck irradiation. Evaluation of 1056 patients

From January 1 to September 30, 1974, we examined 1056 of 5266 subjects (20.1%) who had received therapeutic irradiation primarily for infections and inflammatory disease of the upper respiratory tract at our institution during the 1940's and 1950's. The tonsillar and nasopharyngeal region was the treatment site in 85% of those examined. Palpable nodular thyroid disease was found in 16.5%, and nonpalpable lesions were detected by 99m Tc pertechnetate thyroid imaging in an additional 10.7%, for a prevalence of nodular disease of 27.2%. Operation on 71% with nodular disease revealed thyroid cancer in 33% (60 of 182). Preliminary analysis for potential risk factors suggests a correlation between radiation exposure and the presence of thyroid nodules (P less than 0.001). These findings indicate that nodular thyroid disease, both benign and malignant, continues as a major health problem for at least 35 years in exposed subjects.

Recent developments in radiation-induced carcinoma of the thyroid

At the University of Chicago Hospitals, 40 per cent of patients with a history of irradiation to the neck and a palpable thyroid abnormality have been found recently to have carcinoma of the thyroid at operation. In a study of 100 unselected patients with a history of neck irradiation, 26 had palpatory abnormalities and seven of 15 who were operated upon had carcinoma of the thyroid. Five of these lesions demonstrated evidence of local invasion or lymph node metastases. This prevalence rate of carcinoma of at least 7 per cent in irradiated patients is the highest yet reported. These facts have led us to take a very aggressive position in the treatment of these patients. All patients must be examined carefully. When any palpatory abnormality is present which cannot be explained convincingly by thyroiditis, the patient should be operated upon. Total or near-total thyroidectomy should be performed in each patient by a qualified neck surgeon. In cases of proved carcinoma, a modified radical neck dissection should be added if cervical lymph nodes are clinically involved with tumor. Postoperative thyroid hormone suppression is mandatory and ablation of any residual iodine uptake in the neck or elsewhere by radioactive iodine is advocated. If treatment is aggressive, an excellent prognosis can be expected. However, deaths do occur from this disease. It is imperative that each of us be aware of this disease entity and that we treat these irradiated patients appropriately.

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.

Radiation carcinogenesis

Accidental or therapeutic exposure to radiation may induce tumors of various histologic types in human beings as well as in animals. Two tumors in this report arose in the organs which had been included in the field of radiation 32 and 8 years before, respectively. The author briefly reviews the literature, which abounds with references to radiation carcinogenesis.

Is childhood thyroid cancer a lethal disease?

The clinical, pathological, surgical, postoperative findings and survivorship of 58 patients younger and 513 patients older than 21 years at the time of diagnosis with thyroid neoplasms are reported. The younger patients have a predominance of well differentiated carcinomas which are more likely to be follicular. The lesions tend to be more advanced at the time of diagnosis, are treated by more aggressive surgery in the younger patients and are associated with a much better prognosis. Lack of progression of well to poorly differentiated neoplasms and a greater sensitivity to and dependence upon TSH in young patients, are two factors which may contribute to the striking difference in the prognosis of well differentiated thyroid carcinoma related to age.

Cancer of the thyroid

These relatively infrequent tumors intrigue both clinican and researcher. Each histologic type posesses its own distinctive natural history, controversy surrounds therapeutic programs, and prognosis is influenced by multiple factors, varying from a fatal outcome within a few months to a nearly normal life expectancy. Since fatalities do occur in patients with well differentiated cancers, a more aggressive approach to all thyroid nodules would improve current survival rates.

Thyroid cancer in young patients in Great Britain

Recent collective experience with thyroid cancer in children in Britain is reported. Fifteen out of 16 patients with papillary carcinoma treated in the years 1962–7 are still living at least 5–10 years later; the sixteenth patient died of an unrelated cause. Two patients with follicular carcinoma also survived. Seven deaths between 1957 and 1970 were due to anaplastic or medullary carcinomas and 1 death was caused by a papillary carcinoma.

These data emphasize that in the treatment of papillary carcinoma we should take account of its prolonged natural history. Radical operations which have serious associated morbidity do not appear to be indicated.

Clinical diagnosis of thyroid cancer

In a survey of 293 patients with carcinoma of the thyroid, a goitre or enlarged lymph nodes in the neck were the commonest symptoms and a mass confined to one lobe the commonest sign. Hardness of the mass was an important diagnostic feature, and at least two-thirds of the tumour could be recognized before operation. It is suggested that the preoperative evaluation of thyroid swellings should be classified as benign, cancer suspected, and cancer probable.