The source for this information is "Prescription for Nutritional Healing" by James F. Balch. I borrowed it from my ILs. There are a few contradictions with what pp's have said, but for the most part it all follows (I certainly won't say this is the perfect source of information!)

Recommendations:
Eat a diet that includes grains, nuts, seeds, and unpolished brown rice. Millet cereal is a good source of protein. Eat wheat, oat, and bran.
Eat plenty of cruciferous vegetables (broccoli, Brussels sprouts, cabbage, cauliflower). Also consume yellow and deep-orange vegetables such as carrots, pumpkins, squash, yams. Apples, berries, Brazil nuts, cantaloupe, cherries, grapes, legumes (including chickpeas, lentils, and red beans), and plums all help tp fight cancer. Berries protect DNA from damage.
Cook all sprouts slightly, except alfalfa, which should be eaten raw.
Eat onions and garlic, or take garlic supplements.
Eat 10 raw almonds daily. They contain laetrile, which has anticancer properties.
Drink beet juice (roots and greens), carrot juice (beta-carotene), fresh cabbage juice, and asparagus juice often. Grape, black cherry, and all dark-colored juices are good, as are black currants. Also beneficial is apple juice, if fresh. Fruit juices are best taken in the morning, vegetable juices in the afternoon.
Drink spring or steam-distilled water only, no tap.
Do not consume any of the following: peanuts, junk food, processed refined foods, saturated fats, salt, sugar, or white flour. Instead of salt, use kelp or potassium substitute. If necessary, a small amount of blackstrap molasses or pure maple syrup can be used as sweetener in place of sugar. Use whole wheat or rye instead of shite flour. Do not consumer anything containing alcohol or caffeine. Avoid all teas except herbal teas.
Do not eat any animal protein - never eat luncheon meat, hot dogs, or smoked or cured meats. As your condition imrpoves, eat broiled fish three times a week.
Limit your consumption of dairy products; a little yogurt, kefir, or raw cheese occasionally is enough.
Limit, but do not eliminate altogether, your intake of soybean products; they contain enzyme inhibitors.
Take coffee enemas daily to help the body eliminate toxins. Use clenaing enemas with lemon and water or garlic and water two or three times weekly.
Do not take supplemental iron. The body naturally withholds iron from cancer cells to inhibit their growth,.
Use only glass cookware and wooden cooking utensils.
Get regular exercise. Cancer is less prevalent in physically active people. Exercise also helps to stave off depression and promotes oxygenation of the tissues.
Many people with cancer have acheived good results with a macrobiotic diet.
Kombucha tea has energizing and immune-boosting properties and may be valuable in fighting cancer.