Good news: cancer deaths have declined for the second year in a row. This trend has a number of causes, including fewer smokers and improved treatment options. But one cancer accounts for more than 65 percent of the overall decline in deaths:
By far the greatest decreases in mortality have been in colorectal cancer — 1,110 fewer deaths in men, 1,094 fewer in women.
Dr. Elizabeth Ward, a managing director in epidemiology and surveillance at the cancer society, said the most important factor in the decrease was screening for colorectal cancer, which can detect the disease early when it is most treatable, or even prevent it entirely by finding precancerous polyps, which can be removed before they turn malignant. Progress has been significant even though only about half the adults who should be screened have been. If more people were screened, there would be even steeper declines in death and the incidence of the disease.
So how can we get more people to undergo preventative screening for colon cancer? The main method of screening is a colonoscopy. During a colonoscopy, a small camera mounted on a flexible metal tube is inserted into the large intestine. As you might expect, the procedure is rather painful, and normally lasts about 45 minutes. Many patients don’t return for a follow up colonoscopy precisely because the procedure is so uncomfortable.
So how can we make colonoscopies less painful? In the mid-1990’s, the psychologists Donald Redelmeier and Daniel Kahneman came up with a brilliant method. They studied two groups of patients undergoing colonscopies. One group received a standard colonoscopy. The second group received the same treatment, except that at the very end of the procedure the doctors let the instrument sit in place for a few extra minutes. (This is relatively painless, at least when compared to the probing that comes before.)
Which group experienced less pain? At first glance, the answer seems obvious: the first group would report less overall pain, since their procedure was a few minutes shorter. But this isn’t what happened. The second group experienced significantly less discomfort. Of course, this is a completely counterintuitive reaction, since it implies that the way to make a medical procedure less painful is to make it last longer. According to Kahneman, the only trick is to make the additional minutes represent a relative decrease in the intensity of pain. When doctors listened to Kahneman’s advice, patients were more likely to return for a follow-up colonoscopy.
How did the psychologists explain this counter-intuitive result? According to Kahneman, people judge their sensory experience relative to a reference point, which in this case was the painful sensation of a camera probing their intestine. As a result, when the probe stopped moving, what the subjects perceived was a relative decrease in pain, which felt nice. The happy ending made up for the overall increase in painful moments. (This is known was the peak-end rule.) As Kahneman observes, “A general property of perceptual systems is that they are designed to enhance the accessibility of changes and differences. All perception is reference-dependent.”
PS: I’ve been asked why I spend so much time talking about prospect theory and Kahneman and Tversky. The main reason is that I find their research fascinating and full of relevance to the real world. The other reason is that Kahneman and Tversky play a significant part in my next book (I’m still in research mode).