I've learned more about the suspension from a website we are permitted to mention on this board because it is a US Government website, in fact the website for the National Institutes of Health: www.nih.gov
I feel a little better after reading the full news release, which was published yesterday, October 27, and the associated Q&A. I feel better because of backhanded encouragement: it appears to me that the trial was suspended because of fairly low level yet real concerns about vitamin E at the trial dose of 400 IU as well as slight concerns about selenium, coupled with absence of at least a 25% benefit for prostate cancer based on five year follow-up data for a substantial number of the trial participants. To me that leaves open the possibility that these supplements may yet prove to have a substantial degree of prevention and therapy support punch while having a fine safety profile for most of us.
Jim, you say, you're a cockeyed optimist!
Well, I may be, but I don't think so. Anyway, here's how I'm thinking through this one.
I too feel the dose of E at 400 IU raises a small risk for trial participants who are in the two of four arms of the study that are getting vitamin E. (They don't know that because the study is "blinded" to patients and their doctors. In fact, it's still blinded after the suspension, unless the patient asks which arm he was in.) Vitamin E thins blood slightly, and in some men that can increase the risk of stroke, so men with uncontrolled high blood pressure were ineligible for the study. Of course, it's possible they could develop that problem during the study. More to the point, a study published in 2005, well after the launching of SELECT, showed that patients with vascular disease or diabetes who took 400 IU of vitamin E daily had a 13% higher risk of heart failure than those taking the placebo. Note that that does not mean that 13% had heart failure, it just means their risk was 13% higher than some other number, which I don't know off hand - probably a pretty low risk overall, even if you have diabetes or vascular issues, but a risk large enough to tip the benefit versus risk scale, especially since well over 10,000 men are in the two arms getting vitamin E. In contrast, there seem to be no notable safety issues at a dose of 200 IU of vitamin E daily. The review board could justify continuing the study even after that news about added risk, prior to the recent review, based on expected benefit outweighing risks, but that decision would have become a lot harder to justify when interim SELECT data in September at five years showed no benefit.
Similarly, there is what looks to me like a slight concern that daily selenium may slightly increase the risk of diabetes. The NIH information states that, since the start of enrollment for the SELECT trial, four studies were published on selenium consumption and diabetes. Two found a slightly increased risk, one was neutral, and one indicated a decreased risk. Therefore, the SELECT trial doctors were advised to be alert for diabetes. SELECT trial data did show a slightly increased risk that was not statistically significant, and therefore possibly due to chance.
So far, these facts make me think that I'm on safe ground continuing with just 200 IU of vitamin E, with gamma tocopherol, and 200 mcg of selenium, particularly since I don't have the risk reported factors, and since I am monitored regularly.
Also, it also turns out that in 2003 results of the Prostate Cancer Prevention Trial were published, which initially showed that 5 mg of finasteride (aka Proscar) daily reduced the incidence of prostate cancer by 25%! (There were some safety concerns, which have now gone away - or should have for doctors who are keeping up, and recent evidence is that the actual reduction of PC incidence was 30%.) The trial managers felt ethically bound to bring this to the attention of men in the trial and did so in 2003. Therefore, some men in the trial have no doubt been taking finasteride to lower their risk of prostate cancer. I suspect the number is fairly large considering that men in the trial were motivated to try to prevent prostate cancer in the first place.
The impact of finasteride use on the trial is that it would, by itself, prevent some men from developing prostate cancer at the five year point. This means that there would be fewer men for whom selenium, vitamin E, or the combination could independently prevent prostate cancer, making it harder to achieve prevention of at least 25%.
All that said, the main preliminary study for selenium suggested that it could prevent slightly over 60% of prostate cancer at the 5 year follow-up point, and later follow-up analysis of the same patients only slightly lowered that percentage, to 52% at the 7 1/2 year point. Now that's impressive prevention!!!
It disappoints me that selenium did not at least show a benefit in the 25 - 50% range.
Maybe a high proportion of men in the study took finasteride, and maybe the kind of prevention benefit for selenium and finasteride is similar, though that seems odd. We will need to stay tuned to further reports.