CANCER RISK IN INDIVIDUALS WITH BENIGN THYROID-DISORDERS

The risk of cancer was examined in a cohort of 57,326 individuals who were discharged from a Danish hospital with a diagnosis of myxedema, t hyrotoxicosis, or goiter. Although the general risk of cancer was only slightly increased, the risk of several sites was significantly above expected. The risk of thyroid cancer especially, was increased with s tandardized incidence ratios among women of 2.1 (myxedema), 2.5 (thyro toxicosis), and 6.6 (nontoxic goiter). The increase in risk was presen t even many years after discharge, indicating that surveillance was no t the only explanation. Furthermore, an increased risk was noted for c ancer of the kidney in women discharged with myxedema (standardized in cidence ratios [SIR] = 1.8) and thyrotoxicosis (SIR = 1.3), for cancer of the bladder in women discharged with myxedema (SIR = 1.5) and nont oxic goiter (SIR = 1.3), and for cancer of the hematopoetic system in women discharged with myxedema (SIR = 1.4) and nontoxic goiter (SIR = 1.4). The findings indicate that thyroid disorders may be related to c ancer risk of several specific sites other than the thyroid.