Carcinoma of the thyroid after external radiation to the neck in adults

Pathologic diagnosis of papillary thyroid carcinoma: today and tomorrow

Papillary thyroid carcinoma is the most common malignancy of the thyroid. It is a well-differentiated tumor and the majority behaves in an indolent fashion. The pathologic diagnosis of papillary carcinoma in both cytology and histologic specimens is based upon demonstration of typical nuclear morphology. Using these morphologic criteria, most papillary cancers can be diagnosed with ease, except cases in which there is a paucity of diagnostic nuclear features. Despite advances in the treatment of thyroid cancer, disease recurrences and metastasis can be observed in 20% of cases. Recently, many advances have been made in the pathogenesis of papillary thyroid carcinoma. The notable genetic events include Ret/PTC rearrangements, Ras and BRAF gene mutations. The identification of these has also led to their use in diagnosis and predicting prognosis of papillary thyroid carcinoma. In addition, these involved genes may also serve as targets for cancer chemotherapy in patients where standard thyroid cancer treatment is not effective.

A note from history: Landmarks in history of cancer, Part 6

In the 3 decades from 1940 to 1970, the United States became the nucleus for research, diagnosis, and treatment of cancer. The discovery of anticancer drugs, and the clinical demonstration that chemotherapy and radiation can cure cancer and have the ability to prevent recurrence of cancer, were incontrovertibly the most remarkable groundbreaking events. Consequently, the trend of less surgery and more multimodality therapy began. The introduction of radioautography, mammography, ultrasonography, computed tomography, Papanicolaou smear, and other novel laboratory tests furthered early detection of cancer and refined accurate diagnosis. The unequivocal linking of lung cancer to cigarette smoking made medical history. The delineation of the potential role of oncogenes adduced new thoughts about oncogenesis and cancer prevention, and pathologists finalized the classification and nosology of tumors. Finally, it is worth noting that although more advances were made in the detection, diagnosis, and treatment of cancers than any other period in history, the overall mortality rate of patients with cancer remained high and unchanged.

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.

Thyroid dysfunction and neoplasia in children receiving neck irradiation for cancer

The reported relationship of radiation exposure and thyroid carcinoma stimulated this retrospective study of 298 patients treated at St. Jude Children's Hospital with radiation therapy to the neck for childhood cancer to identify patients who developed subsequent thyroid abnormalities. This series includes 153 patients with Hodgkin's disease, 95 with acute lymphocytic leukemia, 28 with lymphoepithelioma, and 22 with miscellaneous tumors. Inclusion in the study required 5 years of disease-free survival following therapy for their original tumor, which included thyroid irradiation. Follow-up has been 100%. Most patients also received chemotherapy. Seventeen patients were found to have decreased thyroid reserve with normal levels of free triiodothyroxine (T3) or free thyroxin, (T4) and an elevated level of thyroid-stimulating hormone (TSH). In nine patients hypothyroidism developed, with decreased T3 or T4 levels and an elevated level of TSH. One hyperthyroid patient was identified. Two patients had thyroiditis, and seven had thyroid neoplasms: (carcinoma in two, adenoma in two, colloid nodule in one, and undiagnosed nodules in two). This survey has demonstrated an increased incidence of thyroid dysfunction and thyroid neoplasia when compared to the general population. The importance of long-term follow-up for thyroid disease is emphasized in patients who have received thyroid irradiation. The possible role of subclinical hypothyroidism with TSH elevation coupled with radiation damage to the thyroid gland as a model for the development of neoplastic disease is discussed.

Survival of human normal thyroid cells after X-ray irradiation

Normal thyroid cells from 25 individuals treated surgically for malignant or benign thyroid tumour were cultured in vitro and radiation induced cytotoxicity was studied. The mean lethal dose (Do), quasi-threshold (Dq), and extrapolation number (n) of survival curves of actively dividing thyroid cells assayed by colony formation were estimated to be 92.9 +/- 2.8 cGy (rad), 58.1 +/- 6.9 cGy and 2.0 +/- 0.1, respectively (average for 25 individuals +/- standard error). These results suggest that proliferating human thyroid cells are more sensitive to X-rays than most other nonhaematologic mammalian cells in similar assays. Cell survival was not significantly affected by sex, age, disease or exposure to atomic bomb radiation of the cell donor. However, the number of samples currently available is too small for definite conclusions in this regard.

Two cases of lymphoma of the parotid gland following ablative radioiodine therapy for thyroid carcinoma

Two adult patients are described in whom 131I therapy thyroid carcinoma was followed by the development of non-Hodgkin's lymphoma in salivary glands. Histologically one was lymphocytic and the other histiocytic. The total doses of 131I given were 27 GBq (675 mCi) and 14GBq (350 mCi), lymphoma presenting 10 and 3 years respectively after the initial therapeutic dose of 131I. We suggest that the relationship is a causal one, because of the rarity of salivary gland lymphoma and the high dose or radiation to the salivary glands with this mode of therapy.

Osteoclastome-like giant cell thyroid carcinoma controlled by intensive radiation and adriamycin, in a patient with meningioma and multiple myeloma treated by radiation and cytoxan

The eighth cases of osteoclastome-like giant cell carcinoma of the thyroid, and the first one to be treated with adriamycin in addition to surgery and radiation, is reported. This rare variant of anaplastic thyroid carcinoma appeared in a patient operated on for meningioma and treated for multiple myeloma with cranial radiation and chronic administration of cytoxan.

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.

Thyroid neoplasia following irradiation for medulloblastoma: report of two cases

Thyroid neoplasms occurred in two patients 14 and 18 years after treatment with radiation for medulloblastoma. One patient has a papillary cancer and the other patient had multiple adenomas and a Hurthle cell adenoma. In addition, the latter case had foci of hyperplasia plus a microfollicular transformation, which has not been described in association with prior thyroid irradiation. The radiation doses delivered to the thyroid through posterior cervical spinal ports (2000--3000 roentgens) fall within the upper range of radiation dosage associated with induction of neoplastic changes within the thyroid.

Parathyroid adenomas following irradiation

Parathyroid adenomas have been demonstrated to occur following external head and neck irradiation. The median latency interval is 30 years. In a series of 74 consecutive patients with histologically diagnosed parathyroid adenomas, 25% gave a history of prior radiation exposure. When compared to a matched control incidence of 7.9%, statistical significance is reached at p less than 0.01. Thyroid abnormalities were present in 68% of the irradiated patients, and 30% of these were malignant. Tumor of skin, breast, and parotid gland also occurrred more frequently than expected. Forty-seven percent of the irradiated group had malignant neoplasms within the radiation field. The histopathology of the radiation-associated parathyroid adenomas is similar to that seen experimentally.

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.

Thyroid abnormalities following neck irradiation for Hodgkin's disease

Thyroid function and scans were evaluated in fifty disease-free patients 2 to 16 years after receiving neck irradiation for the treatment of Hodgkin's disease. Twenty-five of 50 patients had abnormal thyroid studies: eight were hypothyroid, two were hypothyroid and had abnormal scans, and fifteen had abnormal scans. Of the 15 patients with abnormal scans, one had an isolated elevation of TSH (thyroid stimulating hormone) and one developed exophthalmos. These data, obtained within a relatively short follow-up period, indicate that morphologic and functional abnormalities of the thyroid gland are not uncommon in patients who have received irradiation to the thyroid gland in the course of treatment for Hodgkin's disease. There is need for continuous reevaluation of the thyroid status in such patients.

Hyperparathyroidism in persons treated with X-rays for tuberculous cervical adenitis

Follow-up examinations of one hundred persons treated with x-rays for tuberculous adenitis between 1930 and 1946 have been carried out to determine if there is an increased incidence of hyperparathyroidism (HPT) after radiation exposure. Neck explorations were done in patients with hypercalcemia and signs and symptoms compatible with HPT. Individuals with thyroid masses were also operated upon when examination of fine needle specimens gave suspicions of malignancy. Eleven subjects were found to have developed parathyroid adenoma or hyperplasia. Four other individuals have hypercalcaemia but are asymptomatic. The mean absorbed dose in the parthyroid glands varied between 75 and 2,200 rads. Six individuals received more than 1,200 rads; four of them later developed HPT, while no HPT occurred below a dose of 300 rads. The high incidence of HPT among patients who had been heavily exposed to radiation suggests a cause and effect relationship between radiation treatment and development of HPT.

Radiation-induced peritoneal mesothelioma

A case report of a patient who developed peritoneal mesothelioma 7 years after internal and external irradiation for carcinoma of the cervix is reported. No previous reports of induction of this tumor by irradiation have been found. The subject of radiation-induced tumors and peritoneal mesothelioma is briefly discussed.

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.

A case of hyperparathyroidism associated with radiation to the head and neck area

Hyperparathyroidism due to a hyperfunctioning parathyroid adenoma developed in a 57-year-old woman exposed to radiation for facial hirsutism, in whom other tumors of the head and neck had occurred. The details of history and the implications of causal relationship are presented.

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.