Cancer is often described as a sped-up version of Darwinian evolution. Through a series of advantageous mutations, the tumor—this hopeful monster—becomes fitter and fitter within the ecosystem of your body. Some of the mutations are inherited while others are environmental—the result of a confusion of outside influences. Much less talked about is a third category: the mutations that arise spontaneously from the random copying errors occurring every time a cell divides.
In a paper this year in Science, Cristian Tomasetti and Bert Vogelstein calculated that two-thirds of the overall risk of cancer may come from these errors—entropic "bad luck." The paper set off a storm of outrage among environmentalists and public health officials, many of whom seem to have misunderstood the work or deliberately misrepresented it. And a rival model has since been published in Nature claiming to show that, to the contrary, as much as 90 percent of cancer is environmentally caused. That to me is the least plausible of these dueling reports. As epidemiology marches on, the link between cancer and carcinogen seems ever fuzzier. The powerful and unambiguous link between smoking and lung cancer almost seems like a fluke.
It will be interesting to see how this plays out. But meanwhile I hope that more of the public is beginning to understand that getting cancer usually doesn't mean you did something wrong or that something bad was done to you. Some cancer can be prevented and some can be successfully treated. But for multicellular creatures living in an entropic world, a threshold amount of cancer is probably inevitable.