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January 2, 1991

Selenium and Breast Cancer

Author Affiliations

University of California San Diego

University of California San Diego

JAMA. 1991;265(1):28. doi:10.1001/jama.1991.03460010028016

To the Editor.—  The antiproliferative and antitumorigenic effects of selenium are so well documented that results of epidemiologic studies suggesting the absence of a protective effect against human cancers1 must be subjected to special scrutiny. In principle, inverse associations between cancer risk and variables of selenium status will only be detectable if the selenium gradient in the study population is sufficiently large.Hunter et al1 utilized toenail selenium levels as indexes of selenium status of nurses from 11 US states. The mean toenail selenium levels of 0.822 ±0.18 μg/g are comparable with those previously observed2 for adults in Georgia (0.81 ±0.14 μg/g) or Boston, Mass(0.74±0.13 μg/g), two relatively low-selenium regions of the United States. The narrow range of the values indicates that the dietary selenium intakes of the majority of subjects were similar, and from their magnitude it follows that they were below the threshold at which