The relationship of head and neck irradiation to the subsequent development of thyroid neoplasms

Individuals who have received head and neck radiation for benign conditions have a markedly increased risk of developing thyroid, salivary, and perhaps breast cancer as compared to the general population. Although the relative risk is very high, the absolute risk that any one individual who has had head or neck irradiation will develop a subsequent malignancy is low. Identification of these patients through some type of screening procedure may be beneficial in terms of prevention of subsequent morbidity and perhaps mortality from cancer, especially thyroid and salivary cancer. The risks of any detection or prophylaxis program must be carefully weighed against the probable, but unproved benefits of early detection. A major unresolved question is the natural history of microscopic thyroid carcinoma in the 25 yr-40 yr old radiation exposed population.