Selenium: Good news for bladder cancer, not so good for prostate cancer

Selenium may aid in the prevention of high-risk bladder cancer, according to a study by researchers from Dartmouth Medical School, Lebanon, NH. The news follows a less-encouraging report from the Selenium and Vitamin E Cancer Prevention Trial (SELECT) showing that supplementation with selenium or vitamin E was not associated with a lower risk of prostate cancer.

The Dartmouth study, published in the online issue of Cancer Prevention Research, compared selenium levels in 767 individuals newly diagnosed with bladder cancer with the levels of 1,108 individuals from the general population. In the entire study population, there was no inverse association between selenium and bladder cancer, but women (34%), moderate smokers (39%) and those with p53-positive cancer (43%) had significant reductions in bladder cancer with higher rates of selenium usage.

“There are different pathways by which bladder cancer evolves, and it is thought that one of the major pathways involves alterations in the p53 gene,” said co-author Margaret Karagas, PhD. “Bladder cancers stemming from these alterations are associated with more advanced disease.”

While other studies have shown a similar association between selenium and bladder cancer among women, this study is one of the first to show an association between selenium and p53-positive bladder cancer.

In SELECT, perhaps the largest cancer chemoprevention trial ever conducted, an independent data and safety monitoring committee recommended discontinuation of vitamin E and selenium supplements in 35,533 male study patients. No evidence of benefit from either study agent was convincingly demonstrated and there was no possibility of a benefit to the planned degree with additional follow-up, the authors will report in the Jan. 7 issue of JAMA.