Green Tea Not Panacea for Prostate Cancer

Study finds no effect for men at advanced stage

TUESDAY, April 9, 2002 (HealthDayNews) -- If you're looking for effective treatments for prostate cancer, don't turn to green tea.

Despite promising laboratory research, doctors from the Mayo Clinic report disappointing results from a 22-center study examining the power of green tea in treating advanced prostate cancer in men.

"We thought that the initial research provided a strong enough impetus to take the finding from the laboratory to the clinic to see if cancer patients could derive some benefits from this strategy, but this turned out not to be the case," says lead author Dr. Aminah Jatoi. She presented the findings this week at the annual meeting of the American Cancer Research Association in San Francisco.

While the treatment failed, Jatoi says the work is still worth noting.

"What's special about this study is that we weren't doing cancer prevention; we were doing cancer treatment. And it's important to realize that cancer physicians are committed to helping patients, and we will continue to examine all potential treatments," Jatoi says.

The research looked at 42 men in 22 treatment centers throughout the Northeast, all diagnosed with advanced prostate cancer that had spread to other organs. The study required the men to drink six 1-gram vials of concentrated green tea daily -- equal in potency to about 12 cups of tea a day.

After 30 days, only one of the 42 men experienced a positive result, with a 50 percent reduction in levels of prostate specific androgen, a blood test marker for prostate cancer. However, that change turned out to be only temporary.

The remaining 41 men saw no improvement in their cancer. The study, which was slated to run four months, ended after just 30 days, due to the progression of disease and side effects, which were attributed mainly to the high caffeine content of the tea.

For nutritionist and herbal researcher Samantha Heller, the study results are not surprising, since what works in the lab often doesn't in a clinical setting.

"Much of the research has been done on animals and in test tubes, so the short-and long-term benefits of green tea consumption on disease processes in humans has yet to be determined," Heller says.

That said, she also believes green tea may still hold promise in preventing disease.

"We have only just begun to scratch the surface of the chemical composition of plants and how they affect our bodies," Heller says. Certainly, she says, two or three cups of green tea a day might offer some healthful benefits.

In fact, that is what is suggested by a second green tea study also presented at this week's San Francisco cancer conference.

Here, doctors from the USC/Norris Comprehensive Cancer Center in Los Angeles and the Shanghai Cancer Institute in China report that compounds known as polyphenols, found in great abundance in green tea, have protective effects against the development of esophageal and gastric cancer.

"In our study, we found that men who drank green tea reduced their risk of esophageal cancer and gastric cancer by as much as 50 percent, and that the tea was most protective in those men who were deficient in other antioxidants," says lead author Dr.Can-Lan Sun.

Antioxidants are a group of nutrients believed to protect the body from cancer-causing elements in the environment, such as cigarette smoke. Polyphenols are one type of antioxidant, which are found not only in green tea, but also black tea, grapes, wine, chocolate, and a variety of plant-based foods.

In this study, researchers examined urinary levels of epigallocatechin (EGC) and epicatechin (EC), two chemical markers of polyphenols which reflect tea intake. They measured levels in 190 men with gastric cancer, 42 with esophageal cancer, and 772 men who were cancer-free. All were residents of Shanghai, where the rate of gastric and esophageal cancer is among the highest in the world.

After comparing test results of all the men, scientists report those with the highest levels of EGC in their urine -- indicating the greatest intake of green tea -- had what researchers call a "statistically significant" reduction in gastric and esophageal cancer.

Interestingly, that reduction was greatest in those men who also had low levels of carotene -- another potent antioxidant.

"Our study seems to indicate that the polyphenols in green tea may be especially protective in those who have low levels of other antioxidants, and in this way may help protect against cancer," Sun says.

For Heller, the most important finding is a reaffirmation of the need for adequate intake of foods high in antioxidants.

"The best way to ensure that our bodies are getting the protective health benefits of these compounds and many others contained in plants, is to eat a diet very high in vegetables, whole grains, legumes and fruit -- and drink some green tea, " Heller says.

What To Do

For more information on the health benefits of green tea, check out University of Shizuoka, Hamamatsu College.

To learn more about the health effects of antioxidants, visit The Cornell Cooperative Extension.

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