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• Patients with thyroid cancer benefit from treatment with exogenous thyroid hormone for two reasons: (1) it provides adequate levels of thyroid hormone to peripheral tissues, and (2) it reduces the level of thyrotropin, which may be an important growth factor in patients with differentiated malignant neoplasms. The use of radioactive iodine for thyroid cancer is highly controversial. Its most appropriate applications are in follicular cancers, in older patients, and in distant functioning metastases. Its value in papillary cancer is questionable, particularly in young patients. There is a great need for effective basic and clinical research on the natural course of differentiated thyroid cancer and the effects of specific therapies.(Arch Otolarygnol Head Neck Surg 1986;112:1207-1209)

In the event of a nuclear reactor accident, radioactive materials could be released into the environment: radioisotopes of iodine could constitute a major component of such a release. Upon such exposure, radioiodines could enter the body and accumulate in an unprotected thyroid gland where they would remain for varying periods of time. A number of methods have been proposed to protect those at risk of exposure. Administration of thyroidblocking agents (such as potassium iodide) to exposed populations could be effective, but their use has raised a number of questions since there are considerable gaps in the scientific information available about the possible effects of low-level radiation from radioiodine. In addition, there are only limited data available about potential toxic side effects of potassium iodide distributed widely to large, unsupervised populations. Concern about these issues led the American Thyroid Association to appoint a committee of its members with special interest and competence in these areas to review the problems in detail and develop an advisory statement on the questions at issue for those to whom this matter might be of concern.(JAMA 1984;252:659-661)

In Reply.—Dr Rosler mistakenly assumes that this article was a comparison of radioactive iodine therapy with exogenous thyroid hormone treatment. Instead, its purpose was to evaluate these two adjunctive methods of treatment, each on its own merits and not in competition.I disagree with Dr Rosler's assertion that benefit from thyroid hormone treatment has not been demonstrated. I refer him to the exhaustive review of De Keyser and Van Herle,1 as well as to an animal study performed by Doniach,2 both of which were referenced in my original article. As to the "intense thyrotropin stimulation," it may not exist once the patient has become hyperthyroid, but it certainly can and does exist before that time, particularly if the patient has undergone a total thyroidectomy. Many examples of this have been published, <br/>some referenced in my article. With little or no thyroid tissue remaining after surgery, there will