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Pancreatic cancer tissue

George Johnson is out with a new book, The Cancer Chronicles: Unlocking Medicine’s Deepest Mystery, and is also now at the center of a host of controversies due to some of his conclusions after years of research and writing. You can keep track of the volleys back and forth at his blog, Fire in the Mind. But I want to you pay close attention in particular to a new piece in Discover (print edition), Prehistoric Times: The idea that cancer is a modern disease is a common misconception — one that the fossil record reveals to be untrue. Here’s the big bold assertion: correcting for the greater longevity of modern people the rate of cancer is no higher today than it was in the human past. This is a shocking claim, and bound to cause controversy.


Though I am not able to judge the validity of this assertion in the specifics, it is not implausible on the face of it. Many of the claims for correlations between particular chemicals or environmental inputs and disease later on in life are subject to the problem of numerous confounds. It’s hard to pull signal out of the noise. But it is possible in some cases; the rates of lung cancer for long time smokers being one of the best socially relevant examples. And yet this itself illustrates and important caveat: there are those who don’t seem to have any of the environmental risk factors for lung cancer who nevertheless develop lung cancer. I know this in part because there are individuals who report that once they are diagnosed with lung cancer others whom they encounter begin to subject them to a battery of questions relating to whether they ever smoked, or, whether they lived with a smoker, because the impression is that this sort of cancer demands a lifestyle prior.

Why? An effect demands a cause. This is a common cognitive bias, and we regularly extract spurious patterns to establish transparent causality on the world. Ultimately there is causality…but it is not always so transparent. A lot of biological process is subject to noise and randomness at the level of our perception. Consider that inbred isogenic lineages of simple organisms kept under perfectly homogenized environments such as C. elegans still exhibit phenotypic diversity. Stuff happens for a reason, but we will never really know what the reason is. So we bracket that under “random.”

And this is probably true for cancer as well, and that is tragic and results in existential crises. The real answer to the question “Why me?” is quite often “No one knows, no one will ever know.” It may be that some cancer are due to clear and causal environmental inputs. But almost surely much of it is outside our practical control. On the margin George Johnson may be wrong (e.g., cancer rates may be 10% higher than the past due to toxic chemicals), but in the broader point that cancer has been a biological fact of multicellular existence which strikes somewhat randomly, I believe he is probably right.

This is not an emotionally palatable answer, so Johnson will remain on the receiving end of many attacks for some time to come. He bears a message which is deeply disquieting for the human need for order and just deserts.

(Republished from Discover/GNXP by permission of author or representative)
 
• Category: Science • Tags: Cancer, Health 
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They’re here. The “War Against Cancer” has been stalling for a while now. Is this going to make a difference? I hope so, but I don’t know….

(Republished from Discover/GNXP by permission of author or representative)
 
• Category: Science • Tags: Cancer, Genomics 
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I recently listened to Paul Ewald talk about how a lot of cancer is due to infection on the radio show To the Best of Our Knowledge. That wasn’t too surprising, Ewald has been making the case for a connection between infection and lots of diseases for a while. What jumped out at me is his claim that kissing can spread some of the viruses. Here’s something he told Discover a few years back:

D: How do we get infected with these dangerous pathogens?

PE: Two of the most powerful examples are sexual transmission and kissing transmission, and by that I mean juicy kissing, not just a peck on the cheek. If you think about these modes of transmission, in which it might be a decade before a person has another partner, you realize that rapidly replicating is not very valuable—the winning strategy for the microbe would be to keep a low profile, requiring persistent infections for years. So we would expect that disproportionately, the sexually transmitted pathogens would be involved in causing cancer, or chronic diseases in general. You can test this. Just look at the pathogens that are accepted as causing cancer—Epstein-Barr virus, Kaposi’s sarcoma–associated herpesvirus, human T lymphotropic virus 1—and find out whether they’re transmitted this way. They almost all are. A random sample would yield maybe 15 to 20 percent of pathogens associated with cancer being sexually transmitted, yet the figure is almost 100 percent. When you look at viruses alone, it is 100 percent.

If a lot of kissing and number of sexual partners is predictive of risk of cancer, my immediate thought is that this naturally explains a lot of the cancer that runs in families. Families can pass on genes and cultural norms which would favor or disfavor certain behaviors.

(Republished from Discover/GNXP by permission of author or representative)
 
• Category: Science • Tags: Cancer, Disease, Health 
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Razib Khan
About Razib Khan

"I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. If you want to know more, see the links at http://www.razib.com"