The government is stopping a major study of whether vitamin E and selenium prevent prostate cancer because the supplements aren’t working and there’s a hint of risk.
More than 35,000 men age 50 and older – including hundreds of Spokane residents – have been taking one or both supplements or dummy pills for several years as part of a study called the SELECT trial.
The Spokane men participated in the trial through several cancer clinics, said Dr. Bruce Cutter, an oncologist with Cancer Care Northwest.
The National Cancer Institute announced Monday that the men will get letters in the next few days telling them to stop taking the pills prescribed by the trial. An early review of the data shows neither supplement, taken alone or together, is preventing prostate cancer.
Of more concern, slightly more users of vitamin E alone were getting prostate cancer – and slightly more selenium-only users were getting diabetes, the NCI said.
That doesn’t prove there is a risk from the supplements, the NCI stressed: Neither blip was statistically significant, meaning it could be a coincidence.
Earlier, smaller studies had suggested the nutrients might help, but instead they’ve become the latest failures in a quest to find cancer-preventing dietary supplements.
Cutter urged men who read about the trials and decided to act on their own by buying and taking the over-the-counter drugs to stop.
“This is important for all men,” he said. “It doesn’t work. And maybe there’s a small, very slight possibility it could make things worse.”
Cutter said although the results may be disappointing, at least the large trials will help focus research on other possible cancer cures or preventive measures.
Researchers will continue to track the men’s health for three years. As with most well-designed studies, the participants didn’t know which nutrients they’d been assigned to take or whether they were in the placebo group. If they ask now, doctors will tell them. But researchers say the study’s results will be more accurate if most of the men wait to find that out until the follow-up health tracking is complete.
The study had been scheduled to run through 2011, enough time for the latest-enrolling participants to have taken the supplements for seven years.