A seven-year research trying to find the effects of Vitamin E and selenium supplements on prostate cancer has been halted because, either alone or together, they do not reduce the risk, and may even heighten it, according to media report Wednesday.
The US$114 million study was conducted by U.S. National Cancer Institute, involving more than 35,000 subjects and at 400 sites around the United States.
The result came after researchers began tallying the data and found there were slightly more prostate cancers in men taking vitamin E alone, and slightly more diabetes in men taking only selenium, quite the reverse to the previous expectation that selenium and Vitamin E might decrease the risk of developing prostate cancer by 60 percent and 30 percent by taking alone or together.
"I am afraid it will be the end of the story for large trials of vitamin E and selenium to prevent prostate cancer," said the study investigator Edward M. Messing, professor and chairman of urology and deputy director of the Cancer Center at the University of Rochester. "For vitamin E, that is unfortunate. Probably if given in a more effective form, it would be a protective or even therapeutic agent."
Study participants were told to stop taking the two pills they'd been taking every day since the trial opened in 2001, and were assured that their health would be monitored for roughly the next three years.
"As we continue to monitor the health of these 35,000 men, this information may help us understand why two nutrients that showed strong initial evidence to be able to prevent prostate cancer did not do so," said Cleveland Clinic researcher and study co-chair Eric Klein in a news release.
This is not the first failed trial of supplements' cancer-prevention properties: Studies completed in the 1990s found that beta-carotene supplementation failed to prevent lung cancer, and in fact appeared to increase the odds that male smokers would develop the disease.
(Agencies via Xinhua October 30, 2008)