Green Tea & Breast Cancer

Other researchers reported that an extract from green tea, Polyphenon E, may help inhibit breast cancer by affecting substances called growth factors. Growth factors are involved in the signals that tell breast cancer to grow.

In earlier research, Katherine Crew, MD, assistant professor of medicine and epidemiology at Columbia University Medical Center in New York, had assigned 40 women already treated for breast cancer to take 400, 600, or 800 milligrams of the extract or to take a placebo twice daily for six months.

That was a study to examine any toxic effects of the extract. For the current study, she evaluated blood and urine samples from 34 of the women to see how the extract might work as a cancer fighter.

"We wanted to better understand the biological effects," she says.

"After two months of Polyphenon E, there was a reduction in hepatocyte growth factor," she says. This is one of the growth factors that affect breast cancer cell growth, spread, and invasion. That reduction declined and was not different from the placebo group at four months, however.

It's still too early to recommend green tea extract as a way to prevent breast cancer, Crew says.
Green Tea & Breast Cancer: Perspective

The new research on green tea and breast cancer adds to growing evidence of its benefits, according to Joanne Mortimer, MD, director of the Women's Cancer Program at the City of Hope Comprehensive Cancer Center.

What Do the Antioxidants in Green Tea Do?

One of the antioxidants found almost exclusively in green tea is epigallocatechin-3-gallate (EGCG), which has been at the heart of recent green tea headlines. Overall, research has yielded conflicting results on whether green tea can fight or prevent cancer.

However, one particularly interesting study, presented at a medical conference in 2008, has shown promising results. Researchers at the University of Mississippi Medical Center added EGCG to the drinking water of 10 female mice. An equal number were given plain drinking water. All were later injected with breast cancer cells. In the mice that had ingested EGCG, tumors were 66% smaller than those in the untreated mice. Their tumors also appeared to have less blood supply, suggesting that the EGCG works by inhibiting blood supply to cancer cells.

While green tea has been the subject of other studies, most of these have focused on whether it prevents cancer (among lifelong tea drinkers in Asia, for example), not whether it slows an existing disease process. Results have been mixed, but more controlled and randomized studies on humans are currently in the works.

What Does this Study Mean for Me?

First, it's important to note that the amount of EGCG these mice were given translates to an awful lot of tea for the average human, that is, about 15 to 30 cups each day for 5 weeks. Although that may not be a pace you can keep up with, there's little harm in adding a few cups of green tea to your daily routine.