Copyright Newsweek November 30, 1998

SOCIETY

DR. MITCHELL GAYNOR KNEW A LOT about cancer when he finished his oncology training at Cornell Medical Center, but he didn"t know much about food. So he was flabbergasted when he showed up at Rockefeller University in 1986, for a postdoctoral fellowship in molecular biology, and found everyone buzzing about Brussels sprouts. Laboratory researchers had started discovering dozens of new chemicals in common fruits and vegetables. And in test-tube and animal studies, these obscure compounds were showing a remarkable ability to disrupt the formation of tumors. Today our knowledge of these compounds is exploding. And as scientists learn more about the chemistry of plants and other edibles, they grow ever more hopeful about sparing people from malignancy. "We"ve seen the future," says Gaynor, now head of medical oncology at New York"s Strang Cancer Prevention Center. "And the future is food."

In the three decades since Richard Nixon hauled off and declared war on cancer, America has spent billions pursuing better ways to kill malignant tumors. The quest has generated valuable knowledge and many new therapies. Yet our cancer death rate is roughly the same today as it was in 1970. Despite the best efforts of surgeons and oncologists, Americans die of breast, colon and prostate cancer at five to 30 times the rate of people in many parts of the world. In Thailand and Sri Lanka, somewhere between two and five of every 100,000 women die of breast tumors. In the United States, 30 to 40 meet that fate.

No one denies that diet is a large part of the reason. In a comprehensive analysis published last year, scientists assembled by the World Cancer Research Fund and the American Institute for Cancer Research concluded that poor eating habits account for a third of all cancer-roughly the same proportion attributable to smoking. Gaynor and a few others are now pushing that notion a step further. In a spate of brash new books-"The Breast Cancer Prevention Diet," "Eat to Beat Cancer" and "Dr. Gaynor"s Cancer Prevention Program" - they make the case that anyone can eat to reduce cancer risk, and they lay out specific regimens to follow.

The books are all rooted in the new science of plant chemistry, and they offer similar advice-from eating the right fats to upping your intake of soy. Dr. Bob Arnot, a nonpracticing physician who covers health and medicine for NBC, takes the how-to conceit the farthest in "The Breast Cancer Prevention Diet," prescribing step-by-step programs for young women, older women, breast-cancer survivors and so on. His book has taken off in recent weeks, topping The New York Times best-seller list-and it has set off a burst of controversy. Fran Visco of the National Breast Cancer Coalition calls it "incredibly irresponsible." The American Council on Science and Health, a watchdog group backed by the chemical and food-processing industries, condemns it as a "disservice to women." Several scientists have accused Arnot of overselling their preliminary findings. And the Memorial Sloan-Kettering Cancer Center has asked not to be mentioned in future printings. "To the public we are saying, "Don"t kid yourself," says Dr. Moshe Shike, director of Sloan-Kettering"s cancer-prevention and wellness program. "Don"t think that by eating this diet you"re going to prevent cancer."

THE CRITICS" MAIN OBJECTION - that Arnot offers medical advice without definitive evidence-could be leveled at any of the new books. The fact is, no one knows exactly which foods, in which proportions, offer the best protection against any particular malignancy. Nor does anyone know which of the myriad chemicals in a turnip or tomato does the most to keep our cells intact. Answering such questions will take decades of clinical study. And no matter how much we learn about nutrition, age, heredity and other unknown risk factors will still make prevention an inexact science. For now, the issue is this: should we change our lives on the strength of lab studies and epidemiological associations, or should we live on cheeseburgers until the case for soy burgers is seamless? If you sift through the available evidence, it"s hard not to agree with Dr. Gabriel Feldman, the American Cancer Society"s director of prostate and colorectal cancer. "We don"t need years of research," he says. "If people would implement what we know today, cancer rates would drop. It"s that simple."

To appreciate the links between diet and cancer risk, you need a sense of how tumors arise. They don"t appear out of nowhere. They take years or even decades to produce discernible masses, and our bodies get many chances to eliminate them along the way. The first step in the process is called initiation. It occurs when something alters a cell"s genetic makeup, enabling it to divide more freely than it should. Viruses, chemicals and radiation can all damage DNA, but the most common culprit is plain old oxygen. Just about everything we do generates highly reactive oxygen molecules called free radicals. They bounce around in our cells, stealing electrons from other molecules and prompting them to do the same. These chain reactions can damage cellular DNA, and they"re going on constantly.

Chemical carcinogens pose a similar challenge. Most of them enter the body as harmless "procarcinogens," but become more dangerous as our livers work to eliminate them. The disposal system involves two sets of enzymes-dubbed phase I and phase II-that work in a tight sequence. The phase I enzymes break them into small pieces. The phase II enzymes are supposed to bind with the fragments and shuttle them out of the body, but that requires perfect coordination. If a fragment happens to bind with a strand of cellular DNA, it may alter the genes that govern the cell"s replication rate. And once that happens, the cell not only grows abnormally but generates offspring with the same tendency.

Ominous as they sound, these are allprecancerous changes, and the body is well equipped to handle them. To qualify as cancer, a lesion must weather a second stage of development, known as promotion. If the right fuels are on hand, the transformed cells may replicate aggressively, creating a discernible mass within months. Without a network of blood vessels to deliver nutrients and oxygen, it won"t grow much larger than a pea. But sometimes a small tumor will spit out growth factors that prompt nearby arteries to send out new branches, or capillaries. And once the tumor has its own blood supply, the odds of a reversal are slim. "Potential cancers are regressing all the time," says epidemiologist Linda Koo of the American Health Foundation. Not so vascularized tumors. They tend to invade neighboring tissues and, worse yet, seed the bloodstream with malignant cells that lodge and flourish in other parts of the body.