Cancer and “fate”

Last week, our Seed overlords published on the flagship an Agence France-Presse article about a survey in Britain whose results showed that large numbers of people believe that cancer is due to “fate” rather than risk factors that can be modified to decrease one’s risk of developing the disease:

LONDON (AFP)–More than a quarter of people believe that fate alone will determine whether they get cancer, not their lifestyle choices, according to a survey conducted by charity Cancer Research UK.

The poll of more than 4,000 adults across the country asked people if they thought they could reduce their risk of getting cancer or whether it was out of their hands.

A total of 27 percent of people said cancer was down to fate, with more women than men believing cancer was a matter of destiny than prevention through measures such as quitting smoking or eating healthily.

Among those from the most deprived areas, the figure rose to 43 percent but fell to 14 percent in the most privileged areas.

The survey also found that smokers were 50 percent more likely than non-smokers to believe that getting cancer was the luck of the draw.

Cancer Research UK’s director of cancer information, Dr Lesley Walker, described the results as “worrying”.

She added: “It is alarming that such a large percentage of the British population do not realise that half of all cases of cancer can be prevented by lifestyle changes.

A number of other bloggers have looked at this study and concluded that it means that the British people who reported this are stupid, “really dumb,” or the result of bad education. Even fellow ScienceBlogger Tara piled on a bit.

I beg to differ; none of this is unexpected, and bloggers are reading more into this survey than is warranted. (It’s painfully obvious that none of them have ever actually tried to explain to a patient how such risk factors apply to them personally.) Leave it to a medical student at Over My Med Body to get much closer to the correct interpretation:

If you look at groups of people, you can easily say that smoking increases your risk of many, many cancers. And other lifestyle choices definitely increase your risk of cancer. But look what I said–increased risk. Not guarantee. Not all smokers develop lung cancer, not all smokers develop emphysema. Not all obese people develop diabetes, and not all people who develop diabetes are obese.

You can say that X increases your risk of cancer by 99%, but when you go down to the individual level, that individual has to either develop cancer or NOT develop cancer. We can’t say which smokers will get cancer and which won’t, only that they’re more likely to. There’s still random chance–if you want to call it fate, so be it–that gives people cancer.

So there you are, Brits, you’re right.

If you want to reduce your risk of cancer, heart disease, and other big killers, prevention is the key, and lifestyle changes can do a lot. But we want to accurate for the individual, we don’t know who will get cancer.

Indeed. Translating epidemiological evidence and risk factors into predictions about whether any single patient will get cancer is fraught with difficulty. It’s all probabilities, and we can never tell any single patient whether they will or will not get cancer with much certainty. For example, take what is probably the strongest and certainly most universally recognized common risk factor for lung cancer, smoking. After 50 years, only around 25% of heavy smokers will develop lung cancer. For shorter periods of smoking or less heavy smoking, the risk, although substantial, is even less than that. Granted, heavy smokers have at least a ten times higher risk of lung cancer than nonsmokers, but it still means that most smokers will not get lung cancer during their lifetimes. In that way, “fate,” if by “fate” you mean random chance,” plays a large role. Just how difficult it is to produce prognostic factors that can be used to give a good estimate of individual risk is shown in a large study published in the New England Journal of Medicine last month.

I once cited a very good New York Times article about how difficult it is to convince patients that such risks apply to them. I will cite it again. In it, the Dr. Abigail Zuker is trying to get her mother to exercise a bit, trying to cite studies showing how moderate exercise has health benefits in the elderly, but her mother would have none of it:

Studies,” she says, dripping scorn. “Don’t give me studies. Look at Tee. Look at all the exercise she did. She never stopped exercising. Look what happened to her.”

End of discussion. Tee, her old friend and contemporary, took physical fitness seriously, and wound up bedbound in a nursing home, felled by osteoporosis and strokes, while my mother, who has not broken a sweat in the last 60 years, still totters around on ever-thinning pins. So much for exercise. So much for studies. So much for modern clinical medicine, based on the randomized allocation of treatment and placebo. All that beautiful science, stymied by the single, incontrovertible, inescapable image of Tee, the one who exercised but grew hunched and crippled anyway.

Is Dr. Zuker’s mother “stupid” or “ignorant”? Not from her perspective, and indeed it can all be viewed as a difference in perspective conveyed by this excellent metaphor:

It is medicine’s eternal quest, these days, to sell impressive science to unimpressed patients, and it is hard to think of a group less equipped to do it than doctors. Doctors are specifically trained not to think like normal people, not to see what others see or to reason as others reason. They — er, we — come to operate in an atmosphere so thin, so heady and attenuated with the power of statistical analysis, that one might wonder whether we are really on the same planet as the patients we try to convince of our truths.

“Exercise helps the elderly.” The doctor sees, from a perch suspended somewhere up in the sky, a large football field filled with the elderly. There are thousands of them down there, all dressed in sweats and sneakers, dumbbells at their feet. Half of them are using the dumbbells, or are down on their backs, doing leg lifts. The others just stand around.

Over the years, of course, the ranks thin. The doctor watches, counts. It begins to look as if there are more exercisers left. After decades, there are definitely more exercisers. Of course, there are still a few sloths standing around (and one of them looks suspiciously like my mother). But by and large, the exercisers come to rule the field.

That is the view from on high. Down on the field, of course, the view is quite different. You are standing in a thick crowd, minding your own business, living your life, but you cannot help noting that the man over there threw his back out with all that exercise, and the woman next to you, grunting to lift her dumbbell, had a heart attack. You cannot see to the other end of the field and have no idea what is happening there. But watching all the sweating and grunting and seeing some of those exercisers disappear anyway, you decide to opt out.

You could say the same thing about smoking, drinking, eating fatty food, or whatever risk factor for whatever disease you would like to think of. On the ground, dismissing scientifically demonstrated risk factors for disease may not seem so irrational, and it’s easy to forget that and attribute such resistance to scientific knowledge as being due to ignorance, stupidity, or just plain stubbornness. Indeed, the weaker the risk factor, the more difficult it is to appreciate its danger “o nthe ground.” Smoking increases your risk of premature death by ten-fold or more, and yet everyone still knows examples of smokers who lived to a ripe old age and health freaks who keeled over dead at age 50. On the ground, even for smokers, it can appear that who lives and dies and who gets cancer or doesn’t are largely due to “fate,” particularly if a bit of denial is at work helping people to ignore inconvenient warnings from their doctor or their public health officials that certain unhealthy activities and lifestyles that they enjoy and don’t want to change are unhealthy.

Only people who have never tried to convince patients to change such lifestyles for the benefit of their health would so blithely attribute this belief in “fate” to stupidity or ignorance. In some cases it may be stupidity or ignorance, but in the majority of cases it probably is not. For instance, 90% of the people in the U.K survey knew that smoking increased the odds of developing cancer, and that still didn’t stop a significant proportion from attributing whether smokers get cancer or not to “fate.” It’s all easy from the air to dismiss patients as being “ignorant” or “stupid,” but it won’t help to persuade them that there are indeed actions that they can take themselves to decrease their risk of developing cancer.