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A Diet for Cancer?

The Dean Ornish solution.

WebMD Feature
Reviewed by Craig H. Kliger, MD

Sept. 25, 2000 -- Imagine knowing that cancer is growing in your body, and you're doing nothing to stop it. A significant number of men with prostate cancer opt for just that -- no surgery, no radiation, just checkups every three months to monitor the tumor.

Because prostate cancer often grows very slowly, and because the standard treatments carry the risk of impotence, incontinence, or both, many physicians endorse this "watchful waiting" approach -- especially for older men. Yet for some patients, it can be extraordinarily difficult to take no action against a cancer they know is inside them.

Dean Ornish, MD, thinks there is something these men can do. Ornish, who startled the medical world several years ago when rigorous trials showed that his combined diet, exercise, and stress-reduction program could reverse heart disease, is now turning his attention to prostate cancer. He and his colleagues are testing the notion that low-tech "lifestyle therapy" can slow, stop, or even reverse the disease in men who are diagnosed early. Could it be that what worked for heart disease can work for cancer, too?

The treatment protocol is based on the heart disease program that Ornish developed at the Preventive Medicine Research Institute in Sausalito, Calif. It calls for 65 men to eat a strict diet -- no meat, oil, or dairy products allowed -- and to engage in various stress-reducing activities including daily meditation, yoga, and exercise. Another 65 men, the control group, will make no lifestyle changes. Both sets of patients will receive prostate-specific antigen (PSA) tests -- an indicator of the cancer's status -- and checkups every three months for a year.

What's the Evidence?

The evidence in support of this approach, according to Ornish, comes mostly from epidemiological research showing remarkable differences in the incidence of prostate cancer in different countries. These studies have found that men all over the world are equally likely to have tiny cancerous lesions -- in essence, the germ of a cancerous growth -- in their prostates. But for men living in countries where the national diet tends to be light on meat and heavy on plant-based foods, these lesions appear less likely to develop into detectable -- and potentially harmful -- masses.

Though nobody knows exactly why this is true, it may be that very early prostate cancers are kept in check by a plant-based diet -- or that something about the typical Western diet encourages microscopic lesions to become tumors. Studies in mice, Ornish says, have also shown that prostate tumors grew far more slowly -- and in some cases even regressed -- when the animals ate a diet low in fat.

Further support for this idea came in a study published in the July 2000 issue of the British Journal of Cancer. Researchers at the Imperial Cancer Fund in Oxford, England, found that men who eat a vegan diet have lower levels of a protein known as IGF-1. This protein's role in prostate cancer isn't fully understood, but the researchers say that, as with PSA, high levels of it are often found in men with the disease.

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