Frequency and morphology of malignant tumours of the thyroid before and after the introduction of iodine prophylaxis

Summary Reclassification of malignant goitres surgically removed between 1952–1975 reveals remarkable epidemiological alterations. There is a proportional decrease in undifferentiated carcinoma, which in males also represents an absolute decrease. The decrease is due to a change in maximum incidence from the 5th to the 7th decade. Differentiated carcinomas, especially the papillary tumours, increase. Comparison with findings in Switzerland shows many conformities. Iodine-prophylaxis apparently influences the morphology of thyroid carcinoma, as indicated by the time lag between the introduction of iodine-prophylaxis and the appearance of alterations in incidence. Iodine-prophylaxis, acting in this way, will improve survival rates in thyroid cancer