Radioactive iodine therapy: effect on functioning metastases of adenocarcinoma of the thyroid

A case of metastatic adenocarcinoma of the thyroid is reported in which treatment by means of radioactive iodine has been successful. The patient was completely thyroidectomized for "malignant adenoma" in 1923, with neither thyrotoxicosis then nor hypothyroidism postoperatively; 15 years later there developed classic symptoms of hyperthyroidism and severe pain in the lower back. In October 1939 a pulsating tumor removed from the level of the 12th thoracic vertebra proved to be metastatic thyroid adenocarcinoma (histologically well differentiated, with small follicles and colloid). In the next two years hyperthyroidism increased and roentgenograms revealed new metastases in the lungs, upper part of the right femur, second rib on the left side, left ilium, and skull. Roentgenologic irradiation of the metastases proved ineffectual. In March 1943 a tracer dose of radioactive iodine revealed iodine retention by all the known lesions and no evidence of residual thyroid tissue in the neck. Therapeutic amounts of radioactive iodine were administered orally between May and October 1943. Definite and lasting clinical improvement followed. In April 1944 and March 1945 additional I* was administered with a resultant disappearance of pain, increase in weight, and progressive change in all clinical criteria in the direction of hypothyroidism. Roentgenographic evidence pointed to an arrest if not a regression of the disease. No untoward effects followed this therapy. Radioactive iodine seems to be an effective therapeutic agent in the control of this type of tumor.