Radiation-related thyroid carcinoma

Metastatic pure papillary thyroid carcinoma presenting as a toxic hot nodule

In the majority of cases, carcinoma of the thyroid presents as a cold nodule by radioiodine and Tc-99m sodium pertechnetate scintigraphy. Whereas the presence of a hot nodule usually implies a benign entity, it does not provide complete assurance against thyroid malignancy. Presented is a rare case of metastatic pure papillary thyroid carcinoma appearing as a hot nodule on Tc-99m sodium pertechnetate and I-123 sodium iodide scintigraphy. The implications of such a case, its management, and review of the pertinent literature are discussed.

Sonographic abnormalities of the thyroid gland following radiotherapy in survivors of childhood Hodgkin's disease

The aims of this study were as follows. (1) To demonstrate the spectrum, frequency and changes on follow-up of sonographic abnormalities in the thyroid gland of survivors of Hodgkin's disease who had received radiotherapy to the neck in childhood. (2) To compare the sonographic findings with clinical examination and radionuclide imaging. (3) To investigate the association between the presence or absence of focal sonographic abnormalities with age at radiotherapy, the interval from radiotherapy, the presence of a raised thyroid stimulating hormone (TSH) and the length of time the TSH had been raised. 46 patients were scanned prospectively and rescanned at 6-18 months. The mean age at first sonography was 22.7 years, the median age at radiotherapy was 12.5 years, and the median interval post-radiation was 10.3 years. Sonographic abnormalities were seen in all 46 patients. 45 had diffuse atrophy and 30 had focal sonographic abnormalities. 18 patients developed new focal sonographic abnormalities on follow-up. Focal sonographic abnormalities were more commonly associated with longer duration of a raised TSH. Two patients had thyroid carcinoma. Sonographic abnormalities of the thyroid are common in patients following neck radiotherapy in childhood. Focal abnormalities are usually associated with a longer duration of raised TSH.

Sonography in thyroid carcinoma in children

This paper reviews the clinical, sonographic and pathological findings of 20 children with thyroid carcinoma in an attempt to determine the value and limitations of sonography in thyroid neoplasms in this age group. Although sonography is an excellent technique for the evaluation of thyroid disorders and masses, certain limitations must be kept in mind. Microscopic foci of tumour might be missed and sonography cannot predictably differentiate benign from malignant disease. Previous radiation exposure should increase the level of suspicion for malignancy.

Papillary carcinoma of the thyroid

The clinical behavior and mortality rate of papillary carcinoma of the thyroid varies widely, and clinically insignificant microscopic foci of the disease are frequently found. Dietary iodine and radiation to the head and neck in childhood play a role in etiology. Needle aspiration cytology provides a highly accurate diagnosis. Ultrasound, radioactive iodine, and technetium scans are not specific and should only be used to complete diagnostic studies when aspiration cytology is negative for papillary carcinoma. The most important aspect of prognosis of an individual patient with papillary carcinoma of the thyroid is the age at which the disease is diagnosed, with an excellent prognosis, even in advanced primary disease or extensive lymph node involvement, in children and young adults. A multifactorial clinical risk group definition (AMES) is easy to use and reliably separates patients into low risk and high risk. Since 90% of patients with this disease rarely have metastases or late complications from the cancer, total or subtotal thyroidectomy is necessary in only 10% of cases for later use of postoperative radioactive iodine. More conservative surgical procedures are advised in low-risk patients. Papillary carcinoma incidentally found during operation for other conditions such as Graves disease or thyroiditis and reported first on the permanent pathology reports are always clinically insignificant and completely cured by removal; total thyroidectomy should be completely avoided. Postoperatively, thyroid hormone supplementation may be unnecessary after relatively conservative surgery in selected low-risk patients. Thyroid hormone must be maintained permanently after total or subtotal thyroidectomy.

Head and neck irradiation in childhood: increased risk of developing thyroid disease

A nodule of the thyroid in a patient with a history of prior irradiation to the head and neck area in childhood is more likely to be malignant than a nodule in the general population. Thirty-two of 144 such patients (22%) who came to surgery were found to have a carcinoma of the thyroid. A relative short-term (6 mo) trial with suppressive therapy with a thyroactive agent may be helpful in selecting out those nodules that may be malignant. Although considerable controversy continues to exist as to the proper surgical treatment, our current surgical management involves performing a total extracapsular thyroidectomy.

Suppressive therapy of thyroid nodules in patients with previous radiotherapy to the head and neck

This is a prospective, randomized study of 431 patients with palpable thyroid nodules who had previous radiotherapy for benign disorders of the head and neck area to determine the response of the thyroid nodules to suppressive therapy and the incidence of thyroid cancer in patients who could not be suppressed and had surgery. A complete response was achieved within 6 months in 18.3 percent of the patients, and in an additional 26 percent of patients between 7 and 12 months postoperatively. Twenty percent of the patients showed complete disappearance of nodules after 1 to 2 years of suppressive therapy. Twenty-two percent who underwent surgery showed carcinoma. If suppressive therapy is to be used, a trial of 1 year rather than 3 or 6 months, as often recommended, may be appropriate.

Solitary thyroid nodule: diagnosis and management

Thyroid nodules are common. Most are benign lesions since clinically important thyroid carcinoma is a relatively rare disease. The most sensitive and specific test for the diagnosis of thyroid cancer is fine-needle aspiration biopsy, but its diagnostic accuracy depends upon whether or not one excises all suspicious nodules, thus including them as correctly diagnosed. Nevertheless, fine-needle aspiration biopsy is the most sensitive, specific, and cost-effective test for thyroid cancer. Therapy depends upon the cause of the thyroid nodule.

Benign and malignant thyroid nodules after neck irradiation

A total of 444 persons were examined for the presence of thyroid nodules on average of 43 years after having been treated with x-rays for cervical tuberculous adenitis. Of this total, 101 subjects had undergone surgery for thyroid nodules: 25 for carcinoma (6%) and 76 for benign nodules (17%). Carcinoma occurred with the same frequency in multinodular and uninodular glands. Because of the uneven age distribution in the current series, it could not be decided whether there was a higher susceptibility of the young thyroid to the induction of thyroid carcinoma or benign nodules. The dosage range for the whole series was 0.40 to 50.90 Gy (40-5090 rad). There was a positive correlation between the absorbed radiation dose and the probability of developing benign and malignant thyroid nodules, even after doses of 20 Gy or more. The risk of developing thyroid carcinoma was equal for men and women, while the female-to-male ratio for benign nodules was 2.9:1, indicating that risk factors associated with females are of less importance in irradiated than in nonirradiated populations. The median latency for carcinoma was 40 years, suggesting that the increased risk of thyroid carcinoma after irradiation remains for the rest of the patient's life.

Late complications after irradiation treatment for cervical adenitis in childhood. A 60-year follow-up study

Irradiation against benign cervical adenitis in children was formerly a widely used form of treatment which has caused a great number of late complications, mostly various benign and malignant tumours in the head and neck area, especially in the thyroid gland. In a follow-up study on 63 individuals irradiated at Karlstad Hospital between 1917 and 1929 we found, in addition to these changes, two hitherto not reported complications. Laryngeal stenoses occurred in 27 cases, 17 of which so severe that they eventually required permanent tracheostomies and 11 had fibrous strictures of the upper esophagus, repeated dilatations have been necessary in many of these cases. These complications were mostly seen in those who had been irradiated at an early age, the laryngeal stenoses appear to be caused by a general retardation or inhibition of the normal growth of the laryngeal cartilages resulting in a microlarynx. One possible explanation for these previously not reported sequelae might be the exceptionally high irradiation doses these persons were exposed to up to 60 years ago.

Use of thyroid scans in the selection of surgical patients

The radionuclide scan should not be used for the routine evaluation of the thyroid gland. Instead, it should be used selectively when indicated by careful clinical judgement. The decision as to whether for not to operate should not be based solely on the findings of the thyroid scan. On the other hand, the presence of a solitary cold nodule should not be the only reason for operation in order to exclude the possibility of malignancy, because a significant percentage of thyroid cancers may be found in areas other than cold nodules [4,5]. Again, clinical judgement is the most reliable and cost-effective method to evaluate a thyroid mass.

Prior irradiation and the development of coexistent differentiated thyroid cancer and hyperparathyroidism

Twelve patients with coexistent well-differentiated thyroid carcinoma and primary hyperparathyoidism were studied to determine the frequency of previous radiation exposure. Eight were found to have received prior irradiation. External radiation was administered to the head and neck region for benign conditions such as tonsillar enlargement, acne, scrofula, and thyroid enlargement. One patient received 131I therapy for carcinoma of the thyroid. The observation that 67% of the patients in this series had previous radiation to the head and neck strongly implicates radiation exposure in the development of coexistent well-differentiated thyroid carcinoma and hyperparathyroidism.

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.

Characteristics of 108 thyroid cancers detected by screening in a population with a history of head and neck irradiation

One hundred and eight cases of thyroid cancer have been discovered as a result of screening 1712 individuals from a well defined population known to be at high risk because of prior head or neck irradiation for benign conditions. Of these 198 cancers, 43 (39.8%) were palpable, 27 (25.0%) were detectable by means of thyroid scintigraphy alone, and 38 (35.2%), referred to as incidental carcinomas, were found when the patients were operated on for lesions which approved to be benign. The most striking feature of these cancers was the high frequency of multicentricity (55%) and bilaterality (36%). This high frequency was found in clinically apparent as well as incidental cancers, and could not be accounted for by the operative pathologic techniques of investigation. Of 42 subjects reevaluated at our institution after a mean time of 38 months, 2 had definite and 2 had probable recurrent or residual thyroid disease. The postoperative thyroglobulin levels in subjects with thyroid cancer were proportional to the amount of thyroid tissue remaining. Follow-up evaluation of the entire group did not disclose any differences in the behavior of these thyroid cancers compared to those not associated with radiation.

Radiation-associated thyroid carcinoma

Since February, 1977, 735 patients having a history of receiving radiation therapy for benign conditions of the head and neck areas during infancy and childhood were examined in a thyroid screening program, and 159 patients were found to have palpable thyroid nodules. These patients had thyroid function tests and indirect laryngoscopy and were followed closely on suppression therapy consisting of either Cytomel or thyroid extract. Thyroidectomy was advised in those in whom the nodules persisted or increased in size. This study documents the incidence of carcinoma and other benign pathological changes and postoperative complications in this group of patients. So far, 49 patients had either a lobectomy with isthmusectomy or a total thyroidectomy. Eleven patients were found to have carcinoma (six had papillary, four had mixed papillary and follicular, and one had follicular carcinoma). Three patients had a therapeutic modified neck dissection following the documentation of microscopic involvement of paratracheal lymph nodes. A high incidence of chronic nonspecific thyroiditis, postradiation fibrosis, and follicular adenomas were also found in these patients. Three patients had temporary hypocalcemia (two weeks) and none had wound infection, hematoma, or postoperative nerve palsy. Of patients who had surgical resection, 22.4% showed thyroid carcinoma.