A new case study by Mayo Clinic researchers
provides preliminary evidence to suggest a component of
green tea may lead to clinical improvement in patients
with chronic lymphocytic leukemia (CLL). Findings are
published online in Leukemia Research.
In the small case study, the researchers report on four
patients who appeared to have an improvement in the clinical
state of their disease after starting over-the-counter
products containing epigallocatechin gallate (EGCG), an
extract of green tea. Three of the four patients met the
standard criteria used to define a response treatment
for clinical trials. These same investigators had previously
shown that EGCG kills leukemia cells from patients with
CLL in the test tube by interrupting the communication
signals they need to survive. That study was published
in Blood in 2004.
"The experience of these individuals provides some suggestion
that our previously published laboratory findings may
actually translate into clinical effects for patients
with this disease," says Tait Shanafelt, M.D., Mayo Clinic
hematologist and lead author of the article. Despite these
encouraging preliminary findings, he urges caution. "We
do not know how many patients were taking similar products
and failed to have any benefit. We also do not yet know
the optimal dose that should be used, the frequency with
which patients should take the medication, and what side
effects will be observed with long-term administration."
Dr. Shanafelt and his colleagues say more studies are
needed to determine these things before they would recommend
widespread use by patients. Dr. Shanafelt is also the
lead investigator in an ongoing clinical trial sponsored
by the National Cancer Institute studying pharmacologic
doses of EGCG in pill form for patients with CLL.
CLL is a blood and bone marrow cancer that affects 8,000
to 15,000 new patients each year in the United States.
Its called chronic leukemia because it progresses more
slowly than acute leukemia, and lymphocytic because it
affects a group of white blood cells (lymphocytes), which
typically fight infection.
CLL has no known cure and affects each individual differently.
Some patients may live with it for decades and not require
treatment, while others need immediate chemotherapy, and
some die within months despite therapy. Because the course
of the CLL is so variable, physicians have historically
adopted an attitude of watchful waiting with early-stage
CLL patients. However, new tests, new medications and
a better understanding of the disease have stimulated
interest in clinical trials to evaluate whether options
beyond watchful waiting will better serve some patients.
"Green tea has long been thought to have cancer-prevention
capabilities," says Dr. Shanafelt. "It is exciting that
research is now demonstrating this agent may provide new
hope for CLL patients."
Other Mayo Clinic researchers who collaborated on this
paper included Neil Kay, M.D.; Yean Kit Lee; Timothy Call,
M.D.; Grzegorz Nowakowski, M.D.; David Dingli, M.D., Ph.D.;
and Clive Zent, M.D.