A group of researchers at Mayo Clinc found that green tea extract has kept cancer in check in a majority of chronic lymphocytic leukemia (CLL) patients who used it in a phase II clinical trial. These findings are the latest in a series of Mayo studies to show promise for the therapeutic use of epigallocatechin gallate (EGCG), the major component of green tea, in reducing the number of leukemia cells in patients with CLL.
"Although only a comparative phase III trial can determine whether EGCG can delay progression of CLL, the benefits we have seen in most CLL patients who use the chemical suggest that it has modest clinical activity and may be useful for stabilizing this form of leukemia, potentially slowing it down," says Tait Shanafelt, M.D., a Mayo Clinic hematologist and lead author of the study.
"These studies advance the notion that a nutraceutical like EGCG can and should be studied as cancer preventives," says Neil Kay, M.D., a hematology researcher whose laboratory first tested the green tea extract in leukemic blood cells from CLL patients. "Using nontoxic chemicals to push back cancer growth to delay the need for toxic therapies is a worthy goal in oncology research -- particularly for forms of cancer initially managed by observation such as CLL."
Dr. Shanafelt and Kay did caution that EGCG should never be considered a substitute for chemotherapy. It is important to note that all patients Mayo tested were early stage, asymptomatic CLL patients who would not otherwise be treated until their disease progressed.
CLL is a type of blood cancer that fits between leukemia and lymphoma. When the amount of leukemia cells in the blood and bone marrow increase, as well as when the lymph nodes enlarge, the disease is said to have progressed. 69 percent of CLL patients had a biological response to EGCG as evidenced by a 20 percent or greater sustained reduction in blood lymphocyte count and/or a 50 percent or greater reduction in lymph node size, the researchers say.
"All in all, the treatment was well tolerated with very mild side effects in most patients," Dr. Shanafelt says.
"Without a phase III clinical trial, we cannot make a recommendation that EGCG be used by CLL patients, but those who want to take supplements should consult with their oncologists and need to receive appropriate monitoring using laboratory tests," Dr. Kay says.