OncoLog: M. D. Anderson's report to physicians about advances in cancer care and research.
Rule

From OncoLog, November 2005, Vol. 50, No. 11

Phytoestrogen Consumption May Reduce Lung Cancer Risk

Eating vegetables and other foods that have weak estrogen-like activity appears to reduce the risk of developing lung cancer, researchers at M. D. Anderson have found. The findings were true for both smokers and nonsmokers, said researchers.

In the September 28 issue of the Journal of the American Medical Association, the investigators reported that study participants who ate the highest amount of foods with dietary “phytoestrogens” had a 46% reduced risk of developing lung cancer compared with those who ate the lowest quantity. More than 3,500 people participated in the research—making it the largest case-control study to examine dietary phytoestrogens and lung cancer risk in a U.S. population, according to the researchers.

The researchers also found gender-specific benefits for different classes of phytoestrogens. Men who ate the highest amount of soy-isoflavones lowered their risk of developing lung cancer by 72%, and women who ate the most lignan-containing fruit and vegetables by 41%. For women who also used hormone replacement therapy, the protective effect was further enhanced.

“What we have found is intriguing and supports a small but growing body of evidence that suggests estrogen-like compounds in food may help protect against development of lung and other cancers,” said the study’s lead author, Matthew Schabath, Ph.D., a postdoctoral researcher in the Department of Epidemiology. “But these kinds of studies, which rely on a person’s recall of the food they have eaten months before, have known limitations and require more investigation.”

“The best cancer prevention advice continues to be to stop smoking, and it is clear that all of us can benefit from healthy eating and exercising,” said the study’s principal investigator, Margaret Spitz, M.D., chair of the Department of Epidemiology. “Still, our results generally show that higher intake of these foods resulted in lower lung cancer risk, and that is certainly a tantalizing preliminary finding.”

One of the most intriguing findings, says Dr. Schabath, is that people who had never smoked had a reduced chance of developing the disease if they ate large quantities of phytoestrogen-rich food. “About 15% of lung cancers occur in lifetime ‘never smokers,’ and besides exposures to second-hand smoke, other risk factors for these cancers are yet to be determined.”

The study builds on the group’s 2004 finding that women who used hormone replacement therapy had a lower risk of developing lung cancer than women who did not. The researchers wondered if the same might be true of foods that have naturally occurring low levels of estrogens.

The researchers then divided consumption into three categories of foods that contain phytoestrogens: isoflavones (soybeans and soy products, chickpeas, and red clover), lignans (rye grains, linseeds, carrots, spinach, broccoli, and other vegetables), and coumestrol (beans, peas, clover, spinach, and sprouts). They then divided consumption of these foods into quartiles, from highest use to lowest use, as measured against all participants. They then compared the two groups, and among their findings were:

  • Overall, consumption of phytoestrogens was statistically significantly higher in controls than in cases.
  • The overall reduction in lung cancer risk was 46% for the highest intake of all phytoestrogens from food.
  • For men, statistically significant trends were noted for each class of phytoestrogen when they were consumed at the highest levels. For example, isoflavones reduced lung cancer risk by 44%, and lingans reduced the risk by 27%.
  • In women, only intake of total phytoestrogens from food sources was statistically significantly higher in controls than in cases. High consumption of these foods reduced risk by 34%, but no effect was seen when individual classes of phytoestrogens were evaluated.
The researchers suggest that phytoestrogens may help protect against lung cancer development because they latch onto estrogen receptors that are present in both normal and malignant lung tissue, and this binding could exert a role in the regulation or deregulation of cancer growth. But they cannot say why women, in general, seemed to benefit less than men do from eating high quantities of specific classes of food with phytoestrogens or why former smokers seemed to benefit less. While the results are intriguing, the investigators caution that much more research is needed to prove a definitive chemoprevention effect.

For more information on this topic or for questions about M. D. Anderson’s treatments, programs, or services, call askMDAnderson at (877) MDA-6789.

TopTOP

Home/Current Issue | Previous Issues | Articles by Topic | Patient Education
About Oncolog | Contact OncoLog
Sign Up for E-mail Alerts

©2008 The University of Texas M. D. Anderson Cancer Center
1515 Holcombe Blvd., Houston, TX 77030
1-877-MDA-6789 (USA) / 1-713-792-3245  
 Patient Referral    Legal Statements    Privacy Policy