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June 3, 1997 -- No. 391
Tums, tofu, aspirin: Can they help prevent cancer?
By SUZANNE WOOD
UNC Lineberger Comprehensive Cancer Center
CHAPEL HILL -- What do Tums, tofu, tamoxifen and aspirin have in common?
They may have components that keep people from developing cancer -- a concept called chemoprevention -- according to researchers at the UNC Lineberger Comprehensive Cancer Center.
In looking for ways to prevent cancer, University of North Carolina at Chapel Hill researchers are studying everyday substances such as calcium (found in milk and products such as Tums), soy (a component of tofu), aspirin and tamoxifen, a hormone used successfully to treat cancer.
These chemoprevention trials study the use of natural and synthetic compounds in early, pre-cancerous stages of the disease. If the studies are successful, scientists may not only prevent cancer recurrence in patients, but also possibly prevent cancer in people at higher risk for the disease.
Researchers in the nutrition department in the UNC-CH School of Public Health recently received a grant from the National Cancer Institute to study genistein, a component of soy, and its effects on the formation of prostate cancer cells.
Dr. Steven Zeisel, professor and chair of the department of nutrition and professor of pediatrics, hopes the study will find a correlation between genistein and the deterrence of cancer. Genistein is thought to interrupt signals that make cancer cells grow.
Researchers have found that countries that consume large amounts of soy, like Japan, have fewer instances of cancer, Zeisel said.
The Japanese consume an average of 80 milligrams of soy a day, while people in the United States only consume about 3 milligrams per day, Zeisel said.
We think that this may account for why there is more prostate cancer in the U.S. than in Japan, he said. If we knew that genistein slows cancer's growth, we could give this treatment (instead of, or as a complement to, surgery).
The first phase of the study will test healthy people and patients with prostate cancer to determine the dosage and possible side effects of the genistein supplement, Zeisel said. The second phase, which the NCI will fund after the first phase is completed, will look at how genistein affects prostate cancer patients and whether it deters the growth of new tumors.
Another nutrient under study is calcium and its effect on colon cancer. This study is complete and the results will be published soon, said Dr. Robert Sandler, professor of medicine and epidemiology at UNC-CH. The study tested whether calcium prevented the development of pre-cancerous polyps in the large bowel.
Polyps are the precursors of almost all colon cancers, so if we could prevent polyps, we could prevent cancers, Sandler said. The people in our study all had at least one polyp removed from their large bowel. We know that this group has a 30- to 40-percent chance of having another polyp in three years. We're hoping to decrease that percentage with this treatment.
Sandler also is conducting a chemoprevention trial to learn whether aspirin and folate (folic acid) prevents pre-cancerous polyps. This study is about 18 months old and will be completed in three years.
Not all chemoprevention studies involve natural substances. Tamoxifen, a drug that interferes with the hormone, estrogen, is also being studied as a possible prevention of breast cancer. Working against estrogen -- a hormone that can promote the growth of cancer cells -- tamoxifen has been shown to prevent the recurrence of a breast cancer patient's original disease, as well as the development of new cancers in the opposite breast, said Dr. Stephen Bernard, associate professor of medicine.
Based on these previous studies, researchers believe that tamoxifen could reduce breast-cancer deaths by 30 percent in a study population. The NCI-funded trial began in the spring of 1992.
Until more studies are completed, Sandler and Zeisel suggest that people exercise regularly, maintain their ideal body weight, eat more fruits, vegetables and soy products, and use alcohol in moderation to help prevent cancer or its occurrence.
And although some people may think tofu is unappetizing, here are two recipes that may help the medicine go down a little easier:
1 cup textured vegetable protein
1 cup boiling water
16-ounce can sloppy-joe sauce
4 whole-wheat hamburger rolls
To rehydrate the textured vegetable protein, place it in a medium saucepan and pour the boiling water over it. Simmer until it is tender and the water is almost completely absorbed. Add the sloppy joe sauce and cook over low heat until heated through. To serve, pour the mixture over the hamburger rolls.
This recipe makes four servings. Each serving has 196 calories, 15 grams protein, 2 grams fat and 32 grams carbohydrate. Ten percent of the calories come from fat.
Textured vegetable protein can be found in the bulk food section of the supermarket. This recipe comes from the 1997 Soyfood Directory.
1 cup frozen strawberries
1 frozen banana
1 10-ounce package soft tofu
1/2 cup orange juice
Put all ingredients in blender and blend on high until blended. The recipe makes two servings. Each serving has 175 calories, 5 grams protein, 2 grams fat and 34 grams carbohydrate. Ten percent of the calories come from fat.
For more recipes using soy, check out the Internet site http://www.soyfoods.com.
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News Services contact: Karen Stinneford (email: firstname.lastname@example.org)
Lineberger contact: Dianne Shaw, (919) 966-3036