Just because it’s “natural” and looks like it might work to prevent cancer doesn’t mean it will work to prevent cancer.
That’s the message of today’s announcement from the National Cancer Institute and the Southwest Oncology Group (which is a national research group that does clinical trials in cancer) that they are telling the over 35,000 men participating in a prostate cancer prevention trial to stop taking their pills.
The study, called “SELECT” and which was started in 2001, was based on two earlier trials that found pretty much by accident that it appeared selenium and vitamin E decreased the incidence of prostate cancer.
Both of those studies were designed to primarily look at cancers other than prostate cancer. One, in Finland, was done to see if vitamin E reduced lung cancer incidence and the other examined the impact of selenium on the incidence of skin cancer. In both of the studies, there was tempting data that selenium or vitamin E unexpectedly reduced the risk of prostate cancer.
But those “accidental findings” didn’t hold up in a well-designed clinical trial. Life is not always simple in medical research.
After 7 years, the results are in: An independent review board which monitored the SELECT trial found selenium and vitamin E—either alone or in combination—did not reduce the risk of developing prostate cancer. In fact, there was a small but not significant increase in the incidence of prostate cancer in the men taking only vitamin E and diabetes in the men taking only selenium.
The result: men are being instructed to stop their pills, but will continue to be monitored for several years.
The theories that vitamin E or selenium can reduce the risk of prostate cancer have been around for awhile. There were many men who already believed that vitamin E and selenium could reduce the risk of prostate cancer. But, once subjected to critical study through a randomized clinical trial—the gold standard of medical research—we find the evidence didn’t support the theories.
We have been here before with various vitamins and minerals. And, there are those out there who have been suggesting that other vitamins and minerals can reduce cancer risk.
This blog is no stranger to evidence based medicine. No matter how tempting the reports of success may be, until the right trial is done you simply can’t authoritatively support an unproven theory that a vitamin or anything else can prevent cancer.
Let’s always keep that principle in mind before we start advocating that “this thing” or “that thing” prevents cancer.
Until the evidence is in, the evidence isn’t in.
