Selenium May Increase Nonmelanoma Skin Cancer Risk 40244

Selenium May Increase Nonmelanoma Skin Cancer Risk

BUFFALO, N.Y.--Selenium supplementation does not appear toprevent nonmelanoma carcinomas and may slightly increase the risk of a certaintype of nonmelanoma carcinoma, according to a clinical trial published in theOct. 1 issue of the Journal of the National Cancer Institute (95,19:1477-81, 2003) (http://jncicancerspectrum.oupjournals.org).

Carcinomas--cancers that begin in the cells that cover or line an organ--canoriginate in basal and squamous cells, which are the two cellular layers of theepidermis. Basal cell and squamous cell carcinomas--both considered nonmelanomaskin cancers--are the two most common forms of skin cancer, according to theNational Cancer Institute (NCI). NCI added basal cell carcinoma accounts formore than 90 percent of all skin cancers in the United States and is aslow-growing cancer that does not have a tendency to metastasize. Similarly,squamous cell carcinoma does not spread very often, but it does so more oftenthan basal cell carcinoma.

To study the effects of selenium supplementation on preventing nonmelanomaskin cancers, James R. Marshall, Ph.D., of the Buffalo, N.Y.-based Roswell ParkCancer Institute, and colleagues from across the United States evaluated datafrom the Nutritional Prevention of Cancer Trial, a double blind,placebo-controlled clinical trial designed to test whether 200 mcg/d of selenium(as selenized yeast) would prevent nonmelanoma skin cancer among 1,312 patientswho previously had the disease. Researchers did not find a significantassociation between selenium supplementation and the risk of basal cellcarcinoma, although the mineral was associated with a statistically significantincrease in the risk of squamous cell carcinoma and total nonmelanoma skincancer. "I am not sure what is going on with this agent in the skin,"Marshall told INSIDER. "Clearly, it does not appear to offerprotection against skin cancer. Whether it actually increases risk is not asclear. ... Our best estimate is that selenium does not increase risk bymuch."

In their study, researchers concluded results from the Nutritional Preventionof Cancer Trial showed those at high risk of nonmelanoma skin cancer did notbenefit from selenium supplements. Marshall added these results could have beendue to the possibility of a reaction between selenium and arsenic. Anotherinteresting potential was that the study subjects already had skin damage.Marshall stated, "As we noted in the report, most of these people hadhighly initiated skin that had endured lots of sun damage. It is possible thedamage was irreparable."

Because squamous cell carcinoma is non-fatal, the risks associated withselenium consumption are minor compared to the benefit selenium can provide inpreventing prostate cancer, according to Suzanne Stratton, Ph.D., associateresearch assistant at Tucson, Ariz.-based Arizona Cancer Center and anotherinvestigator on the trial. "My concern when this came out is that the mediagets emotional about things because it makes it more interesting," shesaid. "I don't think it'll hurt the industry. I think it makes it even moreimportant that we study this agent in human beings, as long as people are awareof the risks and the potential for tremendous benefit."