Green tea may help treat a form of adulthood leukemia, if the cases of four patients are any indication, according to a new report.
Doctors at the Mayo Clinic in Rochester, Minnesota, found that of four patients who started drinking green tea or taking green tea extracts, three showed clear improvements in their condition in the following months.
The patients all had chronic lymphocytic leukemia, or CLL, a form of leukemia that usually arises during or after middle-age and typically progresses slowly. Like all types of leukemia, CLL is a cancer of the blood and bone marrow, in which abnormal white blood cells replace healthy blood cells.
What’s particularly interesting about these four cases, according to Dr. Tait Shanafelt, is that the patients all started using green tea on their own last year, after hearing media reports about a lab study Shanafelt and his colleagues conducted.
That study showed that one compound found in green tea, known as EGCG, was able to kill cancer cells that were taken from CLL patients and put in a test tube with the tea compound.
After the findings were published, the doctors became aware of four CLL patients at their center who had started using green tea products and seemed to be doing better.
In interviewing the patients and reviewing their records, the doctors found that three showed signs of a regression in their cancer after they started to drink green tea or take green tea capsules. The fourth had an improvement in her white blood cell count, though her disease remained unchanged by standard criteria.
In one case, the patient had been showing progressive swelling in her lymph nodes - one of the characteristics of CLL - before she starting taking green tea capsules twice a day. Over the next year, her lymph nodes steadily decreased in size, according to findings published online by the journal Leukemia Research.
Another patient showed an improvement in her white blood cell count after she started drinking eight cups of green tea per day.
These cases alone cannot prove that green tea or its extracts conferred the benefits, Shanafelt told Reuters Health.
An answer to that question, he said, awaits the outcome of an ongoing clinical trial he is leading. The study, sponsored by the National Cancer Institute, is testing the effects of a purified EGCG extract in treating CLL.
For now, Shanafelt said, there are many unknowns. For example, the researchers don’t know how many CLL patients might have tried green tea products and failed to improve. Nor is it clear what doses patients should take, or whether high doses over a long period could have side effects.
A number of previous studies have suggested that green tea and extracts of the beverage have cancer-fighting abilities, possibly due to the tea’s concentration of certain antioxidants - compounds that help ward off cell damage that can lead to cancer, heart disease and other ills.
EGCG is thought to be the most potent of these tea antioxidants. The Mayo study from last year suggested that EGCG might induce leukemia cells to self-destruct by interfering with the communication signals they need to survive. But the exact mechanism by which green tea may fight cancer remains unclear.