Blog | Wednesday, January 28, 2015

Cancer and Random Genes: Fortune Favors the Prepared

A recent study in Science purportedly demonstrated that cancer is more random than previously thought. This, predictably, has led to high-profile publications in mainstream media suggesting that cancer results more from “bad luck” than factors over which we exercise some control.

If that epiphany bothered you, I am glad to provide a prompt remedy: It is not true.

The researchers studied the rate of potentially cancer-causing genetic mutations in different tissues, with extrapolations based on a computer model derived from the number and frequency of cell divisions. The research showed that many ominous mutations happen spontaneously, meaning they are not passed down from one generation to the next; and such mutations happen more often in tissues that divide often.

At this point, you should be scratching your head and asking: Didn't they study cancer occurrence in actual people? The answer is no. Didn't they show that lifestyle factors don't influence the rate of mutation? Again, the answer is no.

Perhaps most importantly, the work in isolated tissues was only about mutations, not about clinically-relevant cancers in actual bodies. Gene mutation does not equal cancer.

Cancers are at most only initiated by genetic mutation. For a clinically-relevant cancer to ensue, two additional stages are necessary: promotion and expression. Whether or not a cancer is promoted, progresses, and ultimately expresses itself as a clinical problem is substantially influenced by the environment in which that mutated gene finds itself.

The evidence is entirely overwhelming that how we live influences the likelihood of cancer overall, and that of many specific cancers. Studies show that the very same people, with the very same genes, are subject to higher rates of cancer, along with other chronic diseases, when they leave a healthy, native lifestyle behind, and adopt a more dubious one.

Studies show that some populations around the world get much less cancer, as well as other chronic diseases, not because of genetic advantage, but because of lifestyle advantage, mediated by culture. And perhaps most relevant for those of us not yet living in a blue zone, intervention studies show, over and over and over, that a constellation of healthful lifestyle practices translates into less cancer along with other chronic diseases, just as it translates into more years in life, more life in years.

Potentially cancerous mutations will occur more often in tissues with a higher rate of cell division; that's no great surprise. Some such mutations will occur randomly no matter the care we take of ourselves. And many potentially cancer-causing mutations are spontaneous, not endowed to us by our ancestry. That's what the new study shows.

It establishes nothing at all to refute the substantial preventability of clinically-relevant cancer by lifestyle means. It reports nothing to contradict the large body of evidence already established showing the power of our behavior to influence the behavior of our genes.

Yes, there is a random element in cancer-related mutation. Call it luck or fortune if so inclined, but prepare your defense just the same. Lifestyle choices provide a robust defense against bad outcomes resulting from episodically bad cells. In the life cycle of clinically relevant cancer, as in life generally, fortune favors the prepared.

David L. Katz, MD, FACP, MPH, FACPM, is an internationally renowned authority on nutrition, weight management, and the prevention of chronic disease, and an internationally recognized leader in integrative medicine and patient-centered care. He is a board certified specialist in both Internal Medicine, and Preventive Medicine/Public Health, and Associate Professor (adjunct) in Public Health Practice at the Yale University School of Medicine. He is the Director and founder (1998) of Yale University's Prevention Research Center; Director and founder of the Integrative Medicine Center at Griffin Hospital (2000) in Derby, Conn.; founder and president of the non-profit Turn the Tide Foundation; and formerly the Director of Medical Studies in Public Health at the Yale School of Medicine for eight years. This post originally appeared on his blog at The Huffington Post.