Why do we focus on the least important causes of cancer?
According to the CDC, roughly 50,000 Americans in 2006 were infected with hepatitis B, a key cause of liver cancer, despite the availability of a safe and effective vaccine. And the world's second-leading cause of cancer deaths (subscription required)—stomach malignancies—may largely result from an infection by corkscrew-shaped bacteria called Helicobacter pylori, which infects up to two-thirds of the world's population. No effective vaccine yet exists, but an intriguing 2004 study showed that treating the infection with cheap antibiotics in highly selected patients can eliminate future gastric cancers. Though well-designed, that study was in China, and no similar American research has been done. As a result, no clinical guidelines to prevent gastric cancer from the infection exist here.
Another "natural" cancer cause has a fix that's not a vaccine. According to the CDC, almost 5 billion humans are at risk of aflatoxin exposure. Never heard of it? It's a natural product of mold that grows in peanuts, grains, and milk—and like hepatitis B, a leading cause of liver cancer. Strategies to reduce the toxin, like proper crop storage, genetic engineering to produce resistant plants, and regular food testing, could save thousands upon thousands of lives. But they are underutilized and underfunded in much of the developing world.
With dubious links between cancer and cell phones offered as worry candy, we forget about more important natural environmental causes of cancer like sunlight, which is clearly linked to deadly melanomas. For years, manufacturers have touted the anti-cancer benefits of sunscreen (including a series of full-page magazine ads last year). * How many people realize that the principal cause of melanoma is UV-A radiation, which isn't blocked by many sunscreens? * The Food and Drug Administration doesn't even consider UV-A in its labeling requirements for the product.
The obsession with man-made toxins not only reflects a small-minded view of cancer's causes but hints at a worrisome theme in American public health. Our scattershot approach to preventing cancer subscribes to the cult of personal responsibility, albeit with a recent eco-friendly twist: To really help themselves, goes the thinking, people must simply take charge of their health and avoid cancer-causing, artificial products. Somewhat insidiously, we're starting to believe that cancer mostly is prevented by informing individuals to change their consumption habits—not by proactive, broad-based public-health measures like widespread vaccination or agricultural reform.
For example, we could continue worrying about the unlikely link of folic acid in bread with colon cancer and tell people to buy unfortified bakery goods. Or we could remember that a regular colonoscopy for Americans over 50 could drop colon cancer deaths from current levels by 60 percent and figure out why fewer than half of Americans get them. To lower breast cancer rates, we could tell women to buy hormone-free cosmetics or refrain from using deodorant. Or we could encourage mammography and further study medications like raloxifene, which may prevent breast cancer in selected high-risk women.
In the end, admitting that most cancers have natural causes rightly shifts the focus on cancer prevention away from individual consumers. That's a good thing, since in the end, you can't always shop your way to becoming cancer-free.
Correction, April 16, 2008: The original sentence incorrectly stated that the ad ran recently in the New York Times. (Return to the corrected sentence.)
Correction, April 25, 2008: The orginal sentence stated that no sunscreen blocks UV-A radiation. Some products contain small amounts of zinc oxide and other ingredients that do block a small amount of UV-A. (Return to the corrected sentence.)
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Darshak Sanghavi is Slate's health care columnist. He is chief of pediatric cardiology and associate professor of pediatrics at the University of Massachusetts Medical School as well as the author of A Map of the Child: A Pediatrician's Tour of the Body. Follow him on Twitter.