[Cancer of the thyroid in an area of endemic goiter. "Papillarization" with prophylactic iodization]

Thyroid cancer is characterized by endemic goiter, usually where the insufficiency of iodine has lasted a long time. Prophylactic iodization produces a change in the histological distribution of the thyroid carcinomas, with a significant increase in the quantity of papillary carcinomas and a reduction in that of follicular carcinomas. In autopsies, occult carcinomas of minimal size are, with few exceptions, papillary. The change which is produced by iodization allows us to say that papillary carcinoma is the original carcinoma in the thyroid gland and that the follicular carcinoma, differentiated or less differentiated, may be evolutionary stages derived from the insufficiency of iodine. The insufficiency of iodine would be an active factor in the evolution of papillary thyroid cancer. This reasoning is maintained by the inversion of frequency of thyroid cancer in iodized areas and the remarkable regularity of findings of papillary cancer in autopsies.