But the incidence of non-melanoma skin cancers, when evaluated separately, did not differ between the antioxidant and placebo groups in men or women. In men, there was no difference in any form of skin cancer (including melanoma) between the two groups.
In the antioxidant group, 51 women developed skin cancer, while 30 in the placebo group did. Among the men, 43 in the placebo group and 33 in the antioxidant group got skin cancers.
As for melanoma, the incidence did not differ significantly between the men's treatment group -- 6 in the placebo group and 3 in the antioxidant group got it. But 3 women on placebo and 13 on antioxidants got melanoma -- a significant difference, the researchers said.
Antioxidant studies have yielded mixed results, Hercberg stressed. For example, in previous studies, researchers saw a higher risk of lung cancer in heavy smokers who regularly took high doses of beta-carotene.
Studies have suggested that antioxidant supplements might protect against prostate cancer incidence in men with low blood levels of prostate specific antigen (PSA), Hercberg said. But research has also suggested that the nutrients might increase prostate cancer risk in men with a high PSA. PSA levels are a marker for pre-existing prostate cancer risk.
That could also be happening in the women who got more skin cancers after taking antioxidants, he theorized. If their skin cancer had already been developing, taking an antioxidant might not help, Hercberg speculated.
While the study is interesting, further research is needed to confirm it, said Dr. Ariel Ostad, a spokesman for the Skin Cancer Foundation and a New York City dermatologist not involved in the study.
He said the study did have one serious limitation. "It does not take into account sunscreen use," he said. If the participants tended not to use sunscreen, th