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December 13, 1976

Thyroid Supplements and Breast Cancer

Author Affiliations

University of California Davis

JAMA. 1976;236(24):2743. doi:10.1001/jama.1976.03270250013003

To the Editor.—  From time to time, reports are published suggesting that cancer or other forms of malignant disease may be associated with one type of medication or another. Drs Kapdi and Wolfe suggested a relationship between thyroid supplements for hypothyroidism and breast cancer (236:1124, 1976). They report that patients receiving thyroid supplements not only had a higher incidence of breast cancer than those in the general population, but also that there was a clear-cut increase in the incidence of breast cancer with advancing age (a not unexpected finding), and further, that there was a positive correlation between the duration of therapy with thyroid supplements and the incidence of breast cancer.They quote an article by Levy and Levy (Am Practitioner Digest Treat 2:522-526,1951) suggesting that hypothyroidism might have a protective effect against the development of breast cancer. They further speculate that patients who receive thyroid supplements were deprived of