Selenium study reveals potential cancer fighter

Charles C. Labenz Arizona Daily Wildcat Larry Clark, associate professor of family and community medicine, studies selenium, an essential nutrient the body needs to survive. Clark's research has shown a 63 percent reduction in new prostate cancers in those taking the selenium supplements.

Larry Clark, associate professor of family and community medicine at the College of Medicine, began the study to see if selenium would aid in preventing or slowing skin cancers.

Instead of affecting skin cancer, however, the study showed selenium helped prevent prostate, colon or rectal, and lung cancers. It showed no effect on the occurrence of new skin cancers.

"It was a little bit of a surprise," said Clark, who holds a master of public health doctorate degree.

The 10-year study involved 1,312 participants from the East Coast, and found that those taking the selenium had 37 percent fewer instances of new cancers and half the number of cancer deaths than those taking a placebo.

The study also showed a 63 percent reduction in new prostate cancers in those taking the selenium. The results of the study were released in December in the Journal of the American Medical Association.

Selenium is an essential nutrient that the body needs to survive, Clark said. The best sources of selenium are meats, seafood, grains and dairy products.

The recommended daily allowance of selenium is 55 micrograms for women and 70 micrograms for men, Clark said.

He admitted that his study is far from conclusive, and that several more studies are needed to support and further the conclusions.

He said he is waiting until more studies reinforce the findings before making any sort of public health recommendation that people become pro-active and start taking a selenium supplement to prevent cancer.

The study did not look at whether selenium can prevent the recurrence of cancer, or stop cancer in the body from advancing, but Clark said those are important areas that will be explored.

"This was the first study, and it needs to be replicated and extended to other populations as well," he said.

Clark has designed a second project, to be done locally, which will study prostate cancers. He is waiting for additional funding before beginning his new research.

The mean age of the participants in the first study, all previously treated for skin cancers, was 63. Of the participants, 75 percent were male, immediately suggesting the need for studies with more women to examine whether selenium affects incidents of breast or ovarian cancers.

Anna Giuliano, director of the Minority Cancer Prevention and Control Program at the Arizona Cancer Center, said the study itself was exciting, but also that there are more questions to be answered.

"This was one of the few trials that actually worked, where we saw a reduction in the number of incidents of several different cancers and in the cancer mortality rate," she said.

Giuliano said future focuses for studies are on groups that reflect the population of the country.

The average participant took either the selenium or the placebo for 4 1/2 years. The study was double-blinded, meaning that neither the patient nor the doctors knew who was actually getting selenium pills, Clark said.

Although doctors do not understand exactly how selenium works in the body, Clark said they think the results are a type of "program-cell death."

"The selenium helps the cells in the body that are being transformed into malignant cells commit suicide," he said.

Clark's study, which took place from 1983 to 1993, was initially funded by a $15,000 grant from Nutrition 21, a company that manufactures selenium. Additional funding was provided by the American Institute for Cancer Research, the American Cancer Society and the National Cancer Institute.

Giuliano warned against people running out and taking selenium.

Even though the study results are promising, she said, there is no sure recommendation for the correct dosage of selenium needed.

She said that stores have been selling out of the product, and a better method for preventing cancer would be to take the normal routes such as to stop smoking and get routine exams.

Representatives from several drug and health food stores in Tucson, including University Drug, said they have noticed an increase in their sales of selenium since December.