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Feature
Lifestyle, Cancer and Luck
By Gordon Hull, Associate Professor of Philosophy and Public Policy Director,
Center for Professional and Applied Ethics, UNC-Charlotte
W e are taught in popular culture to believe cancer in mutation, which is to say that more replications means greater odds
its various forms very often is lifestyle-caused. Have of “bad luck” striking. The studies are controversial and certainly
melanoma? Why didn’t you stay out of the sun? do not say, as was widely reported, that up to two-thirds of cancers
Have lung cancer? Why did you smoke? To be sure, are caused by bad luck. But they do say something uncomfortable to
some cancers do not fit this pattern as strongly, but there were still the lifestyle theory of cancer risk: We simply do not know enough to
often lifestyle links. Smoking is believed to be a strong risk factor for know how much of cancer risk is attributable to either hereditary or
pancreatic cancer, for example. Other cancers appear to be hereditary, environmental factors, as opposed to “bad luck.”
though the calculation there is more difficult. The BRCA1/2 mutation
produces a 40-60 percent lifetime risk of breast cancer (and a much As a companion piece published with the second study implies,
higher risk of ovarian cancer), but it turns out to account for only we need to approach the etiology of cancers with a certain
about 5 percent of breast cancers. The BRCA mutation made national epistemic humility. Picking up on a point made in the original
headlines when Angelina Jolie tested positive for it and elected to have studies, the piece considers a case in which several mutations are
a prophylactic double mastectomy. individually necessary and jointly sufficient to initiate cancer in a
given tissue. If only one of them were environmentally induced,
The connection between the lifestyle-hereditary explanations for then avoiding that environmental trigger would be sufficient to
cancer is that both can give people specific things to do to minimize avoid the cancer. But the logic of the example works in several
their risk. We have organized a lot of our health policy around these directions. Suppose there were three necessary mutations — one
injunctions: stop smoking, drink less, consider prophylactic surgery “bad luck” and two environmental (say, smoking). In that case,
if you are a BRCA carrier. They thus contribute to a very popular we likely would advise individuals not to smoke, pointing out that
narrative according to which our current and future health are although many smokers never get cancer (the “bad luck” mutation
investments — make the right lifestyle choices now and see good never occurs), their risk is enormously elevated. But what if there
returns in the future. The right kinds of self-discipline can ensure we were six necessary mutations, only one of which was lifestyle?
maximize our health outcomes. Would we recommend avoiding the lifestyle trigger then? After all,
a patient would have to have a lot of “bad luck” in the statistical
One immediate problem with this narrative is that it transfers sense for the lifestyle trigger to result in cancer.
the burden of disease risk onto individuals who may not be in any
position to avoid it. For example, the residents of St. John the Baptist Presumably, the difficulty in avoiding the lifestyle trigger would
Parish in Louisiana suffer staggering rates of cancer and other health be part of any answer to that question. But here, social justice issues
problems, almost certainly due to the proximity of a neoprene raise their heads again. Who bears the cost of avoidance, and how
chemical plant. These residents, however, are nearly all there because much cost should individuals versus larger entities be asked to
of the accident of their birth into poverty. Asking them to leave is bear? In the case of the Louisiana town, if the cost to its citizens of
asking them to do something they cannot plausibly do. Similarly, avoiding pollution is too high, then what cost might the neoprene
blaming smokers for smoking requires ignoring not just the addictive factory be reasonably asked to bear? To put the point in deliberately
effects of nicotine, but the advertising budget of the tobacco industry, uncomfortable terms, since we are dealing with a population, how
its ability to target younger smokers and its longtime historical many predictable deaths are sufficient to justify a given amount of
concealment of the connection between smoking and disease risk. investment in avoiding an environmental/lifestyle trigger? And, given
Blaming the obese for their condition ignores the many structural that we don’t know the exact proportions of environment, heredity
factors over which they have comparatively little control, including and bad luck, how do we make such a decision?
the ready availability of expensively marketed, calorically-dense but
nutritionally sparse foods. I don’t have answers to these questions, but I do think they
suggest a couple of things. First, any discussion of cancers and their
These challenges to the narrative are social justice issues. But what prevention needs to be approached with both a sense of epistemic
if, in addition, there were more epistemic ones? What if the lifestyle humility and moral salience. Lifestyle-based approaches to cancer
paradigm radically over-estimates the incidence of cancers caused by assume we know a lot about the role of environmental factors, and
lifestyle factors? We have known for a while that cancer incidence is they tend to assign too much responsibility to individuals for avoiding
higher in the elderly, which suggests precisely what a pair of recent those factors. Second, we need to be very careful in deciding when
studies published in “Science” claim. A substantial percentage — to call it an individual responsibility to avoid certain environments
perhaps as high as 65 percent — of the variation in cancer risk or behaviors. This is not just because of social justice issues. It is also
between different tissues can be explained by the number of stem cell because we don’t really understand the etiology of most cancers well
replications in that tissue. More replications means more chances for enough to know when or how much to nudge peoples’ behaviors.
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