Iodine and Cancer

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http://www.liebertonline.com/doi/abs/10.1089/105072501300176435

 

 

Thyroid

 

 

Iodine and Cancer

May 2001, Vol. 11, No. 5: 483-486

 

 

Ulla Feldt-Rasmussen

 

Thyroid carcinomas are the most frequent endocrine malignancies. Among

thyroid carcinomas the most frequent types are the differentiated

forms (follicular, papillary or mixed papillary-follicular), whereas

anaplastic thyroid carcinoma and medullary thyroid carcinomas are

rare. Animal experiments have demonstrated a clear increase in

incidence of thyroid epithelial cell carcinomas after prolonged iodine

deficiency leading to a situation of the thyroid gland by thyrotropin

and possibly other growth factors. However, the overall incidence of

differentiated thyroid carcinoma is generally not considered to be

influenced by the iodine intake of a population, whereas the

distribution of the types of thyroid carcinoma seems to be related to

the intake of iodine, with fewer of the more aggressive follicular and

anaplastic carcinomas and more papillary carcinomas in iodine rich

areas. Populations starting iodine prophylaxis demonstrate an increase

in the ratio of papillary to follicular carcinoma. Because a

population with higher iodine intake usually has fewer benign nodules

in the thyroid gland and the incidence of thyroid carcinomas is

similar to an iodine-deficient region, the diagnostic work-up of

nodules in the thyroid gland may become affected. The incidence of

other cancers, such as breast cancer, may be influenced by the iodine

intake, but too few studies are available at present. The present

article summarizes available data from both epidemiological studies,

animal experiments, and basic gene transfection studies. The overall

incidence for a relationship between iodine and cancer is poor and

future studies are warranted.