Thyroid disease following irradiation for benign conditions

Secondary malignancy among seminoma patients treated with adjuvant radiation therapy

PURPOSE

Early-stage testicular seminoma is among the most radiosensitive tumors, with an overall cure rate of over 90%. Among those cured of the disease by orchiectomy and postoperative irradiation, there is a risk of having a second malignancy. We conducted a study to determine the relative risk of the occurrence of secondary malignancy.

METHODS AND MATERIALS

From 1964 through 1988, 128 patients with histologically confirmed early-stage seminoma of the testis underwent orchiectomy and postoperative irradiation at the Radiation Oncology Center, Mallinckrodt Institute of Radiology, and affiliate hospitals. The follow-up periods ranged from 5 to 29 years, with a median of 11.7 years. The expected rate of developing a second cancer was computed by the standardized incidence ratio using the Connecticut Tumor Registry Database. The rate is based on the number of person-years at risk, taking into account age, gender, and race.

RESULTS

Nine second nontesticular malignancies were found; the time of appearance in years is indicated in brackets: two squamous cell carcinomas of the lung [3, 11], one adenocarcinoma of the rectum [15], one chronic lymphocytic leukemia [2], one adenocarcinoma of the pancreas [14], one diffuse histiocytic lymphoma of the adrenal gland [7], one sarcoma of the pelvis [5], and two transitional cell carcinomas of the renal pelvis and ureter [14, 17]. One patient who developed a contralateral testicular tumor was excluded from risk assessment. The actuarial risk of second nontesticular cancer is 3%, 5%, and 20%, respectively, at 5, 10, and 15 years of follow-up. When compared with the general population, the overall risk of second nontesticular cancer in the study group did not reach the 0.05 significance level, with an observed/expected (O/E) ratio of 2.09 (95% confidence interval, 0.39-3.35). When analyzed by the latency period after radiation treatment, during the period of 11 to 15 years, the risk was higher (O/E ratio of 4.45, 95% confidence interval, 1.22-11.63) than expected. The median duration for developing a second cancer was 11 years for tumors arising from tissues outside the irradiated field and 14 years for those within or near the irradiated area.

CONCLUSIONS

The overall observed incidence of second nontesticular malignancy among patients with early-stage testicular seminoma treated with adjuvant radiation therapy was not significantly increased in comparison with the expected incidence. Clinical implications are discussed.

The impact of geographical, clinical, dietary and radiation-induced features in epidemiology of thyroid cancer

Cancer of the thyroid accounts for less than 1% of all cancers recognised each year, but the incidence is rising. Much of the early work of the epidemiology and aetiology of thyroid cancer was based on the assumption that thyroid cancer can be treated as an entity. The recognition that two distinct types of endocrine cell occur within the thyroid has made it clear that any discussion of the aetiology and epidemiology of thyroid malignancies must take into account the histological classification of these tumours. Moreover, there are difficult problems to be considered when comparing thyroid cancer incidence across tumour registries, because of a lack of standardisation or morbidity data collection, difficulties in histological diagnosis, varying rates of diagnosis of occult papillary carcinoma, and prevalence and techniques of autopsies. So far only a relatively small proportion of thyroid cancer cases can be explained with adequate certainty as regards epidemiology and aetiology. As in cancer in general, the aetiology and epidemiology of thyroid cancer in detail remains unknown in the majority of cases.

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.

The risk of second cancer (SC) in patients treated for testicular seminoma

The exact risk of second cancer (S.C.) following treatment of testicular seminoma is not well determined in most series. At our institution, 122 patients with pure seminoma were treated by orchidectomy followed by radiation therapy from 1951 to 1986. Six were lost to follow-up. For the 116 remaining patients, the overall 5-, 10-, 15- and 20-year survival probability was 95%, 90%, 87%, and 84%, respectively. Eleven patients developed 12 second cancers, with a cumulative risk of 7%, 16%, and 16% at 10, 15, and 20 years, respectively. Overall, the risk of second cancer was increased (O/E = 1.97, p = 0.023). There were 3 controlateral seminoma (O/E = 50, p = 0.001), 2 transitional carcinoma of the bladder (O/E = 6.9, p = 0.035), 2 non-Hodgkin's lymphoma (N.S.), 1 acute myeloblastic leukemia, 1 chronic lymphocytic leukemia, 1 intracranial dysgerminoma, 1 rectal and 1 lung adenocarcinoma. Four tumors developed within the previously irradiated field (O/E = 2.2, N.S.). Excluding second seminoma, the overall risk of second cancer was not significant (O/E = 1.33). Five of the 11 patients with second cancer are currently alive without recurrent cancer. We conclude that patients treated for seminoma have an increased risk of second cancer but the overall prognosis remains excellent. The potential factors responsible for second cancer, including irradiation, are discussed.

Morphologic changes in the thyroid after irradiation for Hodgkin's and non-Hodgkin's lymphoma

Four cases of thyroidectomy for suspected thyroid carcinoma after previous irradiation for Hodgkin's or non-Hodgkin's lymphoma are reviewed. The patients ranged in age from 18 to 33 years at the time of thyroid surgery with an average latency period of 12 years (range, 8-20 years) from radiation therapy to thyroidectomy. All patients had a clinically palpable thyroid nodule, and pathologically showed a pattern of multiple adenomatous nodules with cytologic atypia. The microscopic changes were sufficiently striking to cause the primary pathologist to request consultation to rule out thyroid carcinoma in each case. Fine-needle aspiration was performed in one case and suggested a thyroid neoplasm. The pathologic findings are reviewed and distinction of this lesion from thyroid carcinoma is discussed.

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.

Efficiency of the cervical lead shield during intraoral radiography

The cervical lead shield was compared with the conventional lead apron with regard to efficiency of protection against radiation during a full-month survey (fourteen periapical and two bitewing radiographs). The study was performed on a Temex tissue-equivalent human phantom, and thermoluminescent dosimetry was used to measure radiation absorption in the ovaries, testes, and thyroid gland areas. Results showed that the cervical shield significantly reduces the amount of radiation to the skin in all three areas and is equally as effective as the combination of lead apron and thyroid shield. It is therefore recommended as a protective measure during intraoral radiography.

Thyroid hormone administration in irradiated patients

In a recall clinic for patients at risk for thyroid carcinoma due to a history of radiation in infancy or childhood, a group of patients were randomly offered prospective suppressive L-thyroxine therapy and matched to a radiated nontreated group. With an average of more than two years' follow-up, the thyroid hormone-treated radiated group developed fewer nodules and abnormalities to palpation and also had a statistically significant lessening of minimal palpable abnormalities compared to the nonthyroxine-treated radiated group.

Thyroid carcinoma

The issue of appropriate management for thyroid neoplasms remains unsettled. Confusion concerning histology and classification, controversy as to appropriate therapy, the relative indolence of most differentiated thyroid tumors, and various levels of surgical skill have contributed to the prejudice of various approaches to the management of such neoplasms. It appears unlikely that the controversy will be resolved in the immediate future. If total thyroidectomy can be performed by a skilled surgeon with minimal complications, this approach seems theoretically justifiable for the management of most differentiated tumors, facilitating follow-up postoperatively. Conclusive evidence for improved survival with this rationale is insufficient.

Pediatric endocrine surgery

The pediatric surgeon is in a unique position to understand endocrine surgery and, therefore, is expected to develop considerable expertise in this area. In recent years numerous advances and changes have occurred in pediatric endocrine surgery that have led to greater understanding of the disease processes and syndromes and the development of new diagnostic techniques and surgical approaches.

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.

Hyperparathyroidism following irradiation of benign diseases of the head and neck

In a series of 73 consecutive patients with hyperparathyroidism (HPT) eight patients gave a history of irradiation of head and neck because of benign diseases. The average interval between irradiation and definite diagnosis was 34 years. Intermittent hypercalcaemia was found in three patients. Microscopic examination of pathologic parathyroid glands of three patients showed a predominance of oxyphil cells. Thyroid abnormalities occurred more frequently in irradiated patients than in nonirradiated patients with HPT. Reviewing clinical and experimental data an etiologic role of irradiation in the pathogenesis of HPT appears present.

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-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.

Irradiation induced salivary gland neoplasia

Twenty-six patients with a prior history of irradiation for benign conditions of the head and neck and salivary gland abnormalities are reported. All the patients had preoperative physical findings suggestive of tumor, not glandular infection. Forty-six per cent of the patients had one carcinoma and 11% had two carcinomas within the irradiated field. Eight of the 11 malignant tumors in these 26 patients were in the parotid gland. The nonmalignant salivery changes were similar to those previously reported in glands receiving therapeutic irradiation for carcinoma.

Preoperative physical assessment of thyroid glands in previously irradiated patients

The Evanston Hospital maintains an Irradiated Thyroid Evaluation Clinic that has evaluated 695 patients since 1975. One hundred fourteen patients were retrospectively analyzed, and an attempt was made to correlate the preoperative physical examination with the pathologic specimen after thyroidectomy. There was no statistically significant difference between the incidence of carcinoma in glands containing a single nodule (23 per cent) and in multinodular glands. Postirradiation thyroiditis complicated the physical description of glands preoperatively. The categorization of physical findings served only to identify persistent thyroid abnormalities, which must be explored surgically. The overall incidence of carcinoma in the 114 available cases was 34 per cent, with nodal metastases in 18 per cent of the patients with carcinoma.

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.

Irradiation-induced polyglandular neoplasia of the head and neck

Eighteen patients are presented with twenty-one tumors of the head and neck, which include ten salivary gland tumors and eight parathyroid adenomas. Eight of the patients also had thyroid neoplasms. All patients had a history of prior irradiation to the head and neck. Seventy per cent of the salivary gland tumors and 37 per cent of the thyroid tumors were malignant. Recommendations are made for detection and treatment.