The clinical behavior of radiation-induced thyroid cancer in patients with prior Hodgkin's disease

Open questions and novel concepts in oral cancer surgery

The persistence of cancerous cells after surgery in oral squamous cell carcinoma (OSCC) represents a major challenge, as it often leads to local recurrences and secondary primary tumors, which are eventually responsible for a large proportion of deaths. This persistence is currently evaluated by histological analyses. In this review we discuss some important pitfalls of the histopathological analysis, such as margin evaluation, specimen shrinkage and T staging. In addition, we critically analyze the appropriateness of current surgical techniques in relation to the concept of field cancerization. Finally, we describe some novel imaging and molecular approaches, which might be useful in tailoring surgical resections and encourage the use of OSCC animal models to explore and provide proof of concept of the feasibility and potential clinical utility of innovative surgical protocols.

Clinical behavior of radiation-induced thyroid cancer: factors related to recurrence

BACKGROUND

Whether thyroid cancer is more aggressive in radiation-exposed patients is not resolved. The frequency of aggressive features in post-Chernobyl patients suggests this may be the case. Our aim was to address this question by re-examining the pattern of risk factors for recurrence of thyroid cancers found in a cohort exposed to external radiation.

METHODS

The study population was drawn from a cohort of 4296 people, followed since 1974, who were treated before the age of 16 with conventional external radiation for benign conditions of the head and neck between 1939 and the early 1960s. The study group consisted of 390 patients who had surgically verified thyroid cancer. Potential risk factors for recurrence were evaluated by proportional hazards analysis.

RESULTS

Fifty patients had recurrences an average of 8.7 years after diagnosis while the other 340 patients were followed for an average of 19.7 years. The sooner after radiation exposure the cancer occurred, the more likely it was to recur (hazard ratio, 0.96/year; 95% confidence interval [CI] 0.91-0.99). Taking into account the effect of the onset of screening in 1974, the features predictive of recurrence were younger age at the initial diagnosis (hazard ratio, 0.95/year; 95% CI, 0.91-0.99) and the size of the thyroid cancer (hazard ratio, 1.2/cm; 95% CI, 1.0-1.6).

CONCLUSION

Although not based on a direct comparison, we conclude that thyroid cancers following external radiation exposure are not, on average, more aggressive than other thyroid cancers. The similarity of risk factors for recurrence suggests that they should be treated and followed in the same way as non-radiation-induced thyroid cancers.

Long-term risks for thyroid cancer and other neoplasms after exposure to radiation

Radiation-related thyroid cancer continues to be a clinical concern for two reasons: the risks associated with the widespread use of radiation treatments for benign conditions in the middle of the last century persist for decades after exposure; and radiation continues to be an effective component of the treatment of several childhood malignancies. Patients who were irradiated in the head and neck area need to be evaluated for thyroid cancer, benign thyroid nodules, hyperparathyroidism, salivary-gland neoplasms and neural tumors, including acoustic neuromas. Radiation-related thyroid cancers appear to have the same clinical behavior as other thyroid cancers, but many irradiated patients are entering the age range when more aggressive neoplasms occur. In this paper, we review how to approach the clinical management of a patient with a history of radiation exposure in the thyroid area, and how to treat radiation-exposed patients who develop related neoplasms, especially thyroid cancer.

Thyroid neoplasms after therapeutic radiation for malignancies during childhood or adolescence

BACKGROUND

Recent data indicate that the risk of developing a thyroid neoplasm clearly is increased after high-dose, therapeutic radiation therapy during childhood. To better understand the time course, natural history, and histopathology of thyroid lesions that develop after high-dose irradiation, the authors undertook a retrospective study of all survivors of childhood and adolescent malignancies who were treated at Memorial Sloan-Kettering Cancer Center and who developed a clinically apparent thyroid neoplasm.

METHODS

The authors searched the data base of the Department of Pediatrics, the hospital-based tumor registry, and the hospital medical records database for patients with thyroid neoplasms.

RESULTS

Thirty-three patients were identified who developed a thyroid neoplasm after therapeutic radiation. Primary diagnoses were Hodgkin disease (n = 18 patients), non-Hodgkin lymphoma (n = 10 patients), acute lymphoblastic leukemia (n = 2 patients), acute myeloid leukemia (n = 1 patient), Wilms tumor (n = 1 patient), and neuroblastoma (n = 1 patient). The median age at the time of diagnosis of the primary malignancy was 12.0 years (range, 3.7-18.3 years), the median radiation dose to the thyroid gland was 2400 centigrays (cGy; range, 1000-4200 cGy), and the median interval from the time of radiation therapy until the recognition of thyroid disease was 13.0 years (range, 6.2-30.1 years). Thirteen of 33 thyroid lesions (39%) were malignant (11 papillary carcinomas and 2 follicular carcinomas). Age at diagnosis, gender ratio, and time elapsed since initial treatment did not differ between patients with malignant and benign lesions, but the median radiation dose to the thyroid was lower in patients who had malignant disease compared with patients who had benign disease (2000 cGy vs. 2950 cGy; P = 0.03). Disease was confined to the neck in all patients who had malignant thyroid lesions; after a median follow-up of 6.5 years (range, 0.9-12 years), none of the patients developed progressive or recurrent disease.

CONCLUSIONS

Data from this study suggest that a high proportion of clinically apparent thyroid neoplasms that develop after therapeutic radiation for a childhood malignancy are malignant. However, most of these thyroid malignancies do not appear to behave in an aggressive fashion. Because thyroid neoplasms may not become evident for decades after radiation therapy, all individuals who are at risk require life-long follow-up.

Thyroid dysfunction after mantle irradiation of Hodgkin's disease patients

Thyroid dysfunction can develop in patients with Hodgkin's disease who are treated with mantle irradiation. During the period 1970-89, the records of 320 patients who received mantle irradiation and who had thyroid function tests (TFT) were retrospectively reviewed. The median age was 30 years (range, 7-69 years). The median mantle and thyroid dose was 36 Gy (range, 30-40 Gy) and 39.8 Gy (range, 32-65 Gy), respectively. Overall thyroid dysfunction was present in 39% of the patients. Clinical hypothyroidism was seen in 10% and biochemical hypothyroidism was noted in 25%. Hyperthyroidism was found in 4% of patients. Thyroid nodules had developed in six patients (2%), of which those in four patients were malignant. Age, sex, histological subtype, stage of disease, dose, lymphangiogram and treatment with chemotherapy were not significant factors in the development of thyroid dysfunction. The narrow dose range prevented adequate analysis of dose effect. The results indicate that the incidence of thyroid abnormalities is high enough to warrant regular TFT assessment with pre-irradiation levels and follow-up testing for life because the development of abnormalities can occur many years later. Thyroid examination should form part of the routine follow-up examination and any abnormality should be promptly investigated.

Radiation-induced tumours of the head and neck

In order to study the induction of malignancy in normal tissues due to ionizing radiation, we reviewed the files of 2500 patients with a tumour of the head and neck treated at the Netherlands Cancer Institute (Antoni van Leeuwenhoek Ziekenhuis), Amsterdam, from 1977 to 1993. We then checked whether or not these patients had been previously irradiated. Patients with a thyroid carcinoma or skin cancer were excluded from the study, since it is generally known that previous irradiation is a risk factor in these tumours. Eighteen patients were found to have a malignancy within a previously irradiated area (0.70 per cent). The mean interval between radiation and diagnosis of the head and neck tumour was 36.5 years. There were five soft tissue sarcomas, nine squamous cell carcinomas and four salivary gland tumours. Fourteen patients were operated upon whereas four received palliative treatment only. The median survival of the total group was 3.5 years. Particularly, in young patients because of the better cancer therapy and prolonged survival one must be aware of the increased risk of radiation-induced tumours.

Survival of first and second primary breast cancer

BACKGROUND

A second primary tumor (SPT) in the breast is the most common one seen in clinical practice. There are conflicting reports regarding the incidence and survival of patients with SPT in the breast.

METHODS

To elucidate this, data on 139,932 patients with primary breast cancer, reported to the Surveillance, Epidemiology, and End Results Program between 1973 and 1986, were analyzed. Of these, 3431 patients had a contralateral metachronous breast cancer (interval, > 6 months).

RESULTS

Survival from the date of diagnosis of the metachronous breast tumors was compared with that of patients with single breast tumors, controlling for age at diagnosis, stage, race, and treatment. In the multivariate analysis, age and stage at diagnosis of first and second tumors were the only variables that significantly influenced survival. The survival of patients with localized SPT was similar to that of patients with a localized single breast tumor. Patients with regionally advanced SPT lived for a shorter time than did corresponding patients with only one tumor.

CONCLUSIONS

Patients with single breast cancer were at increased risk of having a SPT in the breast. As a result, efforts for early detection by physical examination and mammography of survivors of single breast cancer are advocated because the survival of patients with a localized SPT in the breast is as good as that of those with a single localized tumor.

A comparison of the clinical characteristics of second primary and single primary sarcoma: a population based study

The clinical characteristics of 240 patients with sarcoma as a second metachronous primary neoplasm (SPN) were compared with those of 8,815 patients with sarcoma as a single tumor. The data were obtained from patients registered during the period 1973-1986 in the Surveillance, Epidemiology and End Results (SEER) Program in the United States. Seventy-four of the 240 SPN patients had postirradiation sarcoma (PIS) while the other 153 patients developed the sarcoma as a second tumor in an area which was not exposed to prior radiotherapy (non-PIS). The stage of disease at diagnosis was more advanced in patients with PIS than in those with single sarcomas but the difference did not reach statistical significance. Overall, in comparable clinical stage localized and regional disease there was no statistically significant difference in survival between PIS and non-PIS sarcoma patients after adjusting for age. The survival of patients with localized or regionally advanced sarcoma as a second tumor was significantly worse than of those with single sarcomas with the same stage. There was no difference in survival between first or second sarcomas with metastatic disease.

A comparison of the clinical characteristics of first and second primary head and neck cancers. A population-based study

The clinical characteristics of 183 patients with second primary neoplasms in the head and neck region were compared with those of 20,598 patients with one primary tumor in the same region registered during the period 1973 to 1984 in the Surveillance, Epidemiology and End-Results Program. Second primary head and neck tumors were more likely to be diagnosed in a localized stage (47%) than if diagnosed as a single primary tumor (43%), but this difference was not significant. The tumor grade distribution was comparable in both groups. Using Cox proportional hazards modeling with age, sex, race, and stage as covariates, the median survival of patients with first and second head and neck cancer was identical (50 months). The survival of patients with localized second head and neck cancer was shorter than that of patients with single localized tumors (55 versus 102 months, P less than 0.026). Survival for regional tumors was similar (18 versus 21 months, not significant). The 84 second head and neck cancers in which the first head and neck cancer received radiation therapy (RT) had a median survival of 20 months; the 98 cases without prior RT had a median survival of 35 months. The high incidence of localized second cancers was probably due to the more intense surveillance. The worse survival in this group may be a result of prior RT or biologic characteristics of the tumor.