Green Tea Cancer Benefits

Research studies have produced inconsistent findings about the cancer benefits of green tea. Studies have shown results of both protective and nonprotective effects of green tea against cancer. These inconsistent results could be due to the different methods of the conduction of the research.

Chemical Composition

According to the University of Maryland Medical Center, green tea contains the richest content of the antioxidant, polyphenols --- generally called catechins --- due to its unfermented leaves. Green tea has six forms of catechins, of which epigallocatechin gallate, or EGCG, has been identified as the most active in fighting free radicals.

Antioxidants, also known as free radical fighters, help prevent ill-health effects induced by free radicals, compounds that can harm the DNA. Free radicals form naturally in the body during the breaking down of foods, and from environmental exposures, such as ultraviolet rays.

Insufficient Amount of Evidence

Although population-based clinical studies have shown some findings that people who drink green tea have a lower risk of cancer development, more research still needs to be done, especially for the claims of lung cancer, stomach cancer and skin cancer prevention, says Medline Plus.

Limited Research Studies

Research studies on cancer benefits of green tea have mainly focused on the Asian populations; thus, the findings in those research studies can't be used to generalize to other populations. According to Medline Plus, research studies suggest that green tea seems to have a protective effect against cancer on Asian-American populations, but not on the Asian populations in Asia.

Hematologic Malignancies

In a study published in 2009 in the "American Journal of Epidemiology," Dr. Toru Naganuma, M.D., and colleagues followed 41,761 Japanese participants for nine years and found an inverse correlational relationship between green tea and hematologic malignancies -- cancer that affects blood, bone marrow and lymph nodes. Participants who drank five cups or more of green tea per day showed a 42 percent decreased risk of the hematologic malignancy development and a 48 percent decreased risk of lymphoid tumor development compared with participants who drank less than 1 cup of green tea per day. The Japanese researchers further stated that a significant reduction of cancer development was observed only in participants who drank 5 cups or more of green tea per day.

Contraindication of Green Tea on Chemotherapy

Recent studies have indicated that green tea could reduce the effect of boronic-acid-based chemotherapeutical drugs, or BZM, on tumor cells. In a 2009 study in the journal "Blood," Dr. Encouse Golden and his colleagues reported that EGCG blocked the function of BZM, but not the function of nonboronic-acid-based drugs. Because of these findings, individuals who are on chemotherapy treatment should consult with their health care provider before including green tea as part of the cancer treatment regimen.