In a surprising finding, daily supplements of the trace element selenium have been found to reduce the risk of several types of cancer in patients with skin cancer history. The results, reported in tomorrow's issue of Journal of the American Medical Association , surprised researchers, which discourage people from loading the supplement until the results are replicated in other people .
A team led by epidemiologist Larry Clark of the Arizona Cancer Center in Tucson had observed lower rates of skin cancer in people with high levels of selenium. So the group has undertaken to test whether selenium could reduce the risk of recurrence of basal cell or squamous cell carcinoma in people previously treated for skin cancer. Beginning in 1983, they began to enroll patients from seven dermatology clinics in the eastern United States, giving half the group a placebo daily and the other half to 0 micrograms of selenium beer yeast tablet. A total of 1312 patients, three quarters were men, received selenium or placebo for an average of 4.5 years.
The group found that selenium was no better than placebo in preventing a return of skin cancer, refuting initial thesis. But he demonstrated some anticancer properties. For example, the selenium group recorded only 77 cases of secondary cancer compared with 119 in the control group. For prostate cancer, the ratio was 13 cases vs. 35; for colorectal cancer, eight against 19; and for lung cancer, 17 against 31. The selenium group also experienced 17% fewer deaths, including half the number of tests from a variety of cancers. The trial was to continue for 2 years, but Clark pulled early decision "so that doctors can know of this potential for cancer prevention."
Experts say the results should be considered with caution. the study is "very, very encouraging," said Clement Ip, a cancer researcher at Roswell Park cancer Institute in Buffalo, but he and others say more studies are needed to determine how selenium affects tumors . and how it affects a broader spectrum of patients There are also questions about its safety when taken on a long term basis: Selenium can lead to hair loss and nail doses above 1 milligram . "We recommend that we do an additional test to confirm these results and see how it spread to other people," said Clark, especially women and people with certain types of cancer.
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