At the age of 31, while Dr. David Servan-Schreiber was testing his own brain-scanning machine, he discovered that he had a malignant brain tumor the size of a walnut. When he asked his oncologist for guidance on diet and lifestyle, the answer was typical: Just do what you're doing.

But according to Servan-Schreiber, now 47, a clinical professor of psychiatry at the University of Pittsburgh School of Medicine and the author of "Anticancer: A New Way of Life" (Viking, 2008), we can do more to prevent or control cancer.

Q. Cancer seems so confusing. Can you give us a brief explanation?

A. Cancer cells develop all the time in a healthy body. They are simply cells that, like rebel armed bandits, have learned to escape the rules of organized society. They no longer respond to signals from neighboring cells and tissues telling them that they are overcrowding others and should stop multiplying.

We are all equipped with natural defenses that can counteract these rebel cells before they have become large armies, and that can prevent them from developing into dangerous tumors.

Q. What's the biggest cancer myth?

A. That cancer is a genetic lottery and that you inherit your cancer risk from your parents' genes. When our lifestyle (85 percent contribution), or our genetic makeup (15 percent) either support cancer growth or interfere with our natural defenses, cancer develops. Yes, cancer runs in families, but that is because our parents pass on their poor lifestyle habits, which matter more than their genes.

Q. Do you believe that you can prevent cancer with diet alone?

A. The World Cancer Research Fund estimates that at least 40 percent of cancers could be prevented with diet and physical activity alone.

Q. How does the traditional American diet create conditions for cancer to thrive?

A. Look at the American national dish: hamburger and French fries, with a white bun and ketchup. You couldn't do better if you wanted to try to promote cancer growth: red meat (the No. 1 food ingredient associated with a variety of cancers), grown on corn and soy (which remove the healthy omega-3s found in grass-fed meat) and bovine growth hormone (which stimulates all cell growth, including cancer cells); french fries: a rare vegetable that does not help slow cancer growth but, on the contrary, stimulates insulin release and thus cell growth, dipped in omega-6 inflammation-promoting oil and fried to increased oxidative stress; white bread: which again stimulates insulin release; ketchup: a rich source of high-fructose corn syrup, associated with insulin resistance and obesity.

In addition, our insistence on eating mostly meat (10.5 ounces per day, when the World Cancer Research Fund advocates 12 ounces per week) greatly reduces the amount of cancer-fighting vegetables in our diet.

Q. What's an anti-cancer diet?

A. The most documented healthy diet is the Mediterranean diet. It does not "eliminate" anything really, just creates a very favorable balance among nutrients. It adds spices and herbs, and does include some lean meats (though preferably grass-fed for a good balance of omega-3s).

Q. What are some of the most surprising foods that help fight cancer?

A. The spice turmeric (the yellow powder that is the basis of curry), has been thoroughly documented to be a powerful anti-inflammatory and anti-cancer agent — though only when mixed with black pepper or ginger. And also green tea. Who would have thought that such a simple beverage could have such powerful effects?

Q. What are some of the most surprising foods that may cause cancer?

A. White sugar and white flour. I had never heard of their relationship to cancer before.

Q. Can you tell us how stress feeds cancer and suggest ways to achieve life balance and good nutrition to combat it?

A. It is not stress itself, but our reaction to stress. Prolonged reactions of despair and powerlessness are associated with disturbed levels of cortisol secretion and noradrenaline, which affect immune cells and their ability to fight cancer. They also stimulate inflammation, which feeds cancer growth.

Simple stress-management techniques, such as proper breathing during times of unrelenting pressure, can help.

Q. What about artificial sweeteners (including stevia)?

A. Animal studies suggest there may be a risk with most artificial sweeteners, except xylitol (a natural birch and corn extract), which seems really safe. My suggestion is to avoid them if you already have cancer.

Q. How about food additives?

A. Recently, animal studies have demonstrated that phosphate-based additives stimulate the growth of lung tumors. I inform all my patients with lung cancer to avoid these additives, which are common in processed foods (cured meats, industrial baked goods and most sodas).

Q. Can you pinpoint what helped control your brain cancer?

A. I believe that there are synergistic interactions when you start to combine nutrition, physical activity, stress management and reduction of toxicity in the environment.

Q. What do you consider the three most perfect foods to help prevent cancer?

A. The spice turmeric, broccoli and green tea.

Q. What's always in your fridge?

A. Omega-3 eggs, for a very quick meal (sunny side up, fried in olive oil with garlic, turmeric, black pepper and a sprinkle of agave nectar).

Q. What food would we never find in your fridge?

A. So many, I cannot begin to list them, but certainly no ice cream.

Q. Do you eat any "junk food"?

A. Sorry, I don't. I do eat chocolate every day, though. But, of course, dark chocolate that is 70 percent cocoa (or more) is an anti-cancer food!

Q. What's the one message you wish you could get into people's heads?

A. That there are no magical cures for cancer, but that we all have tremendous control over our health and well being through the choices we make in our lifestyle every day.

Charles Stuart Platkin is a nutrition and public-health advocate, and author of "Breaking the FAT Pattern" (Plume, 2006). Sign up for the free Diet Detective newsletter at www.dietdetective.com.