Tuesday, November 17, 2009

Mammograms, Zetia/Vytorin, Proscar,Folic Acid

I have received many phone calls from my patients and e-mails from readers on my bloglist about 3 different reports about medical research results: an article in the NY Times by Gina Kolata(Proscar), a report from a cardiac conference(Zetia/Vytorin), and recommendations from a medical study group (mammograms). I received no inquiries about an article in Lancet (folic acid), but I guess few people read British medical journals, even though Lancet antedates both NEJM and JAMA, and their letters to the editor are invaluable. My comments on these are probably applicable to many reports of medical results, and I leave it to my readers to evaluate any such reports.

First, some general comments. In many areas of non-precise science (I am therefore excluding mathematics, chemistry and physics) when recommendations are made, there is both a majority report/recommendation, and a minority report. However, in medicine, except as a rebuttal to a journal article (e.g. the discussion in Lancet as to whether or not reducing total salt in the diet saves lives) we never see the minority report. I doubt that 20 doctors (or 20 anyones) ever agree 100% on a committee report, and it would be nice to see the minority report (cf. the arguments about global warming) so we can try to make our own decision. Furthermore, most refereed journal articles require the authors to make the source data available on request, but this does not happen with medical committee recommendations, so we have no way to judge how they arrived at their recommendations, or what compromises were made (e.g. how did the government first decide that total cholesterol levels should be below 240?). Was it the same way that Congress decided on 27.5% as the oil depletion allowance, i.e. a compromise?

The recent recommendations on the starting age and frequency of mammograms are a case in point. There was no minority report, and the data on which the recommendations were made are not available. I only fear that HMO's will seize on this report to pay for fewer mammograms, as Medicare once did. I have never had a problem with ordering a test for a patient even if I was absolutely certain the result would be negative, because the patient's peace of mind is important to me.
There is absolutely no way to know for a given individual how often a mammogram should be done (why not every 6 months to detect fast-growing cancers?), or at what age the mammograms should start. I also have some 90 year old women who have never had a mammogram, and have never had breast cancer, and so far they are right as well.

The article about men not taking Proscar even though men on Proscar have a lower incidence of prostate cancer did not properly emphasize the fact that if prostate cancer does occur when a man is taking Proscar it is much more aggressive, and has a higher Gleason score. On the other hand, taking both Proscar and Flomax decreases a man's probability of needing a TURP of the prostate to relieve blockage caused by a growing prostate. Also, some men do not like taking Proscar because it diminishes the amount of fluid in the ejaculate by at least 50%, and these men do not enjoy the different sensation, because their orgasms are therefore shorter. Why not just say that men who do not take Proscar are "pharmacologically autonomous"?

Both Zetia and Vytorin decrease cholesterol, which is all the FDA required them to do. Studies on other statins as well as on Niacin showed that lowering cholesterol by these chemicals reduced the risk of second heart attacks and strokes, as well as the risk of first heart attacks. (I have never seen a study on diet, lower cholesterol, and heart attacks.) The FDA then assumed that any chemical lowering of cholesterol was beneficial, as does the entire medical establishment.
The study of Zetia/Vytorin showed that they did not cause regression of the narrowing of the intima of a major artery. However, this is a secondary surrogate marker for strokes and heart attacks. If heart attacks are caused by rupture of plaque (as many cardiologists believe) then stabilizing the plaque (are statins anti-inflammatory as aspirin is?) is more important than the lumen diameter, after a certain narrowing. No one has shown that lowering the cholesterol with Zetia or Vytorin does NOT reduce the risk of heart attack or stroke, just as no one has shown that intimal regression is a valid surrogate for MI's and CVA's.

The latest issue of Lancet reported a large study that showed that fortifying the diet with folic acid, which successfully lowered neural tube defects in infants, INCREASED the risk of cancer. I wonder what the USA and FDA will do with this study. It certainly should be repeated. But studies showing that vitamin ingestion can cause problems rarely make headlines in America. Maybe we should revise the recent recommendations which raised the RDA for folate from 0.4mg to 0.8mg?

Thought for the month: Why does the full moon appear larger when it rises in the East than it does when it is directly overhead?

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