The beginnings of radioiodine therapy of metastatic thyroid carcinoma: a memoir of Samuel M. Seidlin, M. D. (1895-1955) and his celebrated patient.

Emerging from a stimulating encounter over fifty years ago between Dr. S. M. Seidlin and a celebrated patient at Montefiore Hospital in New York City are a number of findings that bear significantly on the contemporary practice of medicine relating to targeted radioisotope therapy. In 1943, Seidlin administered radioiodine to this patient, who was hyperthyroid although previously thyroidectomized, but who had several metastases from adenocarcinoma of the thyroid which localized the radioisotope. Seidlin recognized early that some thyroid metastases would take up radioiodine (i.e., function), but only after the normal thyroid gland was ablated, an essential preliminary procedure before radioiodine therapy should be administered, the clinical practice followed to this day. He held that removing the normal thyroid increased TSH production and eliminated the gland's competition for radioiodine, inducing the metastases to function. From 1942 until his death in 1955, Seidlin and his group followed many patients having metastatic thyroid carcinoma, conducting fruitful investigations concerned with the induction of function, dosimetry, and the occurrence of leukemia in some massively treated patients.