Vitamin E and selenium didn’t prevent prostate cancer

 Medscape reports that SELECT (Selenium and Vitamin E Cancer Prevention Trial) is asking more than 35,000 adult men to stop taking these supplements because of an apparent lack of benefit and a possibility of harm.

But are we sure about this?

Preliminary results revealed that the antioxidants selenium and vitamin E taken alone or together for about 5 years, didn’t prevent prostate cancer. And, it was unlikely that taking them longer would have resulted in a 25% reduction in prostate cancer — the goal of the study. There were also trends (not statistically significant) suggesting risks of this treatment.

The rationale for the study was based on earlier results from the Nutritional Prevention of Cancer Trial — a skin cancer trial of 1312 men and women — where it was observed coincidently that men taking selenium for more than 7.5 years had about 52% fewer new cases of prostate cancer than men taking placebo.

The bottom line?
Earlier this year, Dr. Nick Wareham, who is Director of the MRC Epidemiology Unit at the University of Cambridge in the UK, advocated for a greater role for applied pharmacogenomics to identify and control risk factors for diabetes.

In fact, a test based on pharmacogenomics that identifies diabetic patients at highest risk of cardiovascular complications recently became available. And there is evidence that this special group — about two-thirds of diabetics — benefits from taking vitamin E.

My point is that even in large well-designed studies of CAM, such as SELECT, negative conclusions might mean that the treatment doesn’t’ work. But it might also mean that we simply lack the knowledge needed to select the correct group of patients to study.

10/31/08 17:49 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.