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May 22, 1967

Mammary Gland Dysplasia in Iodine Deficiency: Studies in Rats

Author Affiliations

From the departments of obstetrics and gynecology, medicine, and pathology, Woman's Medical College of Pennsylvania, Philadelphia.

JAMA. 1967;200(8):691-695. doi:10.1001/jama.1967.03120210077014

Epidemiological studies suggest that persons living in areas of normal iodine availability show less breast cancer than those living in iodine-deficient areas.1,2 World Health Organization investigations, recently published,3 have revealed that a large segment of the population in the United States and other parts of the world lives in areas of limited iodine availability. In addition, there appears to be statistical evidence of an increased incidence of breast malignancy in hypothyroidism.4-6 Our results imply that iodine deficiency may be involved in these thyroid-breast relationships.

The breasts of chronically iodine-deficient female rats treated with testosterone were observed to be considerably larger than their normally fed, testosterone-injected litter-mate controls. No reports directly pertaining to this observation were found in the literature. Therefore, we decided to carry out a systematic investigation of the influence of iodine deficiency on the resting and sex-hormone-treated breasts of female rats. The changes seen were