Meditations of an oncology geek

Archive for November, 2012

Deciphering the mess: bias is associated with poor health!

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27 November 2012

Why is it that those that faithfully take their sugar pill placebo consistently have better outcomes than those that don’t? I’m really glad a friend of mine sent me this NY Times article by Gary Taubes: Do We Really Know What Makes Us Healthy?

I had not adequately appreciated the bias of healthy users and compliance: “At its simplest, the problem is that people who faithfully engage in activities that are good for them — taking a drug as prescribed, for instance, or eating what they believe is a healthy diet — are fundamentally different from those who don’t. One thing epidemiologists have established with certainty, for example, is that women who take H.R.T. {hormone replacement therapy} differ from those who don’t in many ways, virtually all of which associate with lower heart-disease risk: they’re thinner; they have fewer risk factors for heart disease to begin with; they tend to be more educated and wealthier; to exercise more; and to be generally more health conscious.”

Science produces a constantly revised version of reality based off of new data. This can be vexing for those looking to draw health recommendations, as often our views become more enlightened and change. But this causes an extra problem for preventive medicine: how can one know that a recommendation is not doing harm? If vitamin Z was good for me yesterday, why is it not recommended now?

Preventive medicine epidemiology has several glaring, inherent flaws. It’s actually very easy to find positive correlations (A and B occur together) between pretty much anything. Conversely, it’s nearly impossible to establish causation (A leads to B) for anything. The reason why is an ethical one: how can one be certain that a preventive medicine being tested won’t do more hard than good? It’s a bit of a catch-22; there’s really no way of predicting harmful effects beforehand, and as a result, well controlled clinical trials are rarely done on healthy humans for preventive purposes. I.e. vitamin Z could be extremely harmful if taken at 1mg/kg body weight for all we know.

Media bias can be especially damning to the process. The first report in any epidemiological study of new association is almost always incorrect, or at least that’s what the statistics say. It takes time for any new idea or association to be re-tested and analyzed by other groups than the one doing the study. Unfortunately, these first reports are often the ones reported in the news media (see above comic). Even worse, the news media often spices up their own interpretations to get their viewers’ attention, further confounding the truth, then fail to follow-up on more nuanced, less sensationalized studies that follow in the wake of an initial discovery. I.e. the ones that would provide better health information or advice.

It’s all very frustrating to this scientific apprentice. But at least forcing myself to write about it helps me keep track of important ideas as I move forward into positions of influence. For that, I have you to thank, dear reader. Without you I might not have taken the time to educate myself as comprehensively!

Ryon

Written by Ryon

November 27th, 2012 at 10:49 am

Posted in Science Blog

Blind Mole Rat anti-cancer, anti-aging secrets explained. Sort of.

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15 November 2012

Original Research Commentary

I came across an interesting article the other day: Cancer resistance in the blind mole rat is mediated by concerted necrotic cell death mechanism (1) Apparently, the blind mole rat almost never develops cancer, and is an unusually long-lived species of rodent. While mice and rats have a maximum lifespan of ~5 years, the blind mole rat can live as long as 21 years. The authors claim that in 40 years of keeping the blind mole rat in captivity at their facilities, that they have never seen a case of spontaneous cancer in the blind mole rat.

Though, I find this claim somewhat hard to believe, unless the authors have done full autopsies (a time and labor-intensive practice) on all their dead blind mole rats for the last 40 years. Regardless, the authors uncover an interesting characteristic of cells taken from the animals: after a certain amount of divisions in a row, the cells all die in a coordinated cell suicide in culture. This does not happen in human cells in culture, nor does it happen to cells from other rodent species.

So, one would predict that a developing tumor in a blind mole rat would spontaneously regress after a few rounds of rapid proliferation (which would theoretically only happen in adults in the case of a developing tumor). It seems fairly straightforward, almost too straightforward…

The authors then found that culture media (the fluid kept on top of cells kept on culture dishes) from the cells undergoing coordinated cell death could induce the same thing in younger cell cultures, making it likely that it was a factor secreted by the cells that caused this hypothetical anti-cancer response. Through several methods, the authors determined that the concentration of a factor known as Interferon-Beta (INF-B) closely mirrored this coordinated cell death, and claim this as the mechanism.

However, the authors did not report inducing this massive, coordinated cell death in response to purified INF-B, which would have been a causative experiment, not a correlation observation. There are likely thousands of factors in the media, and any one of them (or a combination of them together) could be the causative agent(s). Also, this medium containing whatever factors are responsible for this putative anti-cancer response do not have the same effect on human cells, which brings into question the translatability of this phenomenon to therapies in humans.

My verdict: I am not sure if the authors have identified the correct mechanism, but the longevity of the blind mole rat and its purported lack of cancer is a phenomenon that might yield future insights into graceful, disease free aging in another long-lived species: homo sapiens.

Ryon

Written by Ryon

November 16th, 2012 at 11:43 am

Posted in Science Blog