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Lewis H. Kuller, MD, DrPH
University of Pittsburgh Pittsburgh, Pa

JAMA. 1997;277(11):880.

	Since this article does not have an abstract, we have provided the first 150 words of the full text PDF and any section headings.

To the Editor.

—The article by Clark et al¹ has very important implications. The results suggest that increased selenium intake results in a substantial reduction in cancer incidence in only 5 years. This is especially remarkable with regard to lung cancer, since the effects of smoking cessation usually require a much longer follow-up.² These results can be due to (1) a true beneficial effect of selenium; (2) random variation, ie, type I error; and (3) an unexplained higher rate in the control group; in other words, the differences are not due to the benefit of selenium, but due to a much higher rate in the control group than would be expected. Unfortunately, the authors do not provide information on age- and sex-specific cancer rates in either group or the age distribution of cancer cases. They report a mean age of 63 years at entry, 75% men, and approximately 8000 person-years of observation. . . . [Full Text PDF of this Article]

Footnotes
Edited by Margaret A. Winker, MD, Senior Editor, and Phil B. Fontanarosa, MD, Senior Editor.

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