Does green tea prevent cancer?

[Al-khiyal]

Does green tea prevent cancer?
Evidence continues to brew, but questions remain

PHILADELPHIA, November 5, 2009 -- Although scientists are reluctant to officially endorse green tea as a cancer prevention method, evidence continues to grow about its protective effects, including results of a new study published in Cancer Prevention Research, a journal of the American Association for Cancer Research, which suggests some reduction in oral cancer. Vassiliki Papadimitrakopoulo, M.D., professor of medicine in the Department of Thoracic/Head and Neck Medical Oncology at the University of Texas M. D. Anderson Cancer Center, and colleagues tested green tea extract taken orally for three months at three doses among 41 patients: 500 mg/m2, 750 mg/m2 or 1,000 mg/m2. The researchers assessed clinical response in oral pre-malignant lesions and found 58.8 percent of patients at the highest doses displayed clinical response, compared with 18.2 percent among those taking placebo. They also observed a trend toward improved histology, and a trend towards improvement in a handful of biomarkers that may be important in predicting cancer development. Patients were followed for 27.5 months and at the end of the study period, 15 developed oral cancer. Although there was no difference in oral cancer development overall between those who took green tea and those who did not, patients who presented with mild to moderate dysplasia had a longer time to develop oral cancer if they took green tea extract.

Although encouraged by the results, Papadimitrakopoulo cautioned against any recommendations that green tea could definitely prevent cancer. "This is a phase II study with a very limited number of patients who took what would be the equivalent of drinking eight to 10 cups of green tea every single day," said Papadimitrakopoulo. "We cannot with certainty claim prevention benefits from a trial this size." Dong Shin, M.D., professor of hematology and medical oncology and Blomeyer Endowed Chair in Cancer Research at Emory School of Medicine, agreed, but said this trial is certainly a step in the right direction. "A clinical trial with a natural compound is no easy task, and these researchers have accomplished that," said Shin, an editorial board member of Cancer Prevention Research. "The lack of toxicity is also important because often when you give supplements at higher doses than what would occur naturally, you induce nausea and vomiting. That did not happen in this trial."

Neither researcher had a reason why patients concerned about cancer should not drink green tea, but they cautioned against relying on the beverage to definitively reduce their risk of cancer. "The goal of this kind of research is to determine whether or not these supplements have long-term prevention effects. More research including studies in which individuals at high risk are exposed to these supplements for longer time period is still needed to answer that sort of question," said Papadimitrakopoulou.

Source: American Association for Cancer Research

[Al-khiyal]

Green tea shows promise as chemoprevention agent for oral cancer, M. D. Anderson study finds

HOUSTON, November 5, 2009 -- Green tea extract has shown promise as cancer prevention agent for oral cancer in patients with a pre-malignant condition known as oral leukoplakia, according to researchers at The University of Texas M. D. Anderson Cancer Center. The study, published online in Cancer Prevention Research, is the first to examine green tea as a chemopreventative agent in this high-risk patient population. The researchers found that more than half of the oral leukoplakia patients who took the extract had a clinical response. Long investigated in laboratory, epidemiological and clinical settings for several cancer types, green tea is rich in polyphenols, which have been known to inhibit carcinogenesis in preclinical models. Still, clinical results have been mixed.

"While still very early, and not definitive proof that green tea is an effective preventive agent, these results certainly encourage more study for patients at highest risk for oral cancer," said Vassiliki Papadimitrakopoulou, M.D., professor in M. D. Anderson's Department of Thoracic/Head and Neck Medical Oncology, and the study's senior author. "The extract's lack of toxicity is attractive - in prevention trials, it's very important to remember that these are otherwise healthy individuals and we need to ensure that agents studied produce no harm."

In the Phase II dose-finding study, 41 M. D. Anderson oral leukoplakia patients were randomized between August 2002 and March 2008 to receive either green tea extract or placebo. Participants took the extract, an oral agent, for three months at one of three doses - 500 per meter squared of body mass (mg/m2); 750 mg/m2 or 1,000 mg/m2 - three times daily. To best assess biomarkers, participants also underwent a baseline and 12-week biopsy, an important component in the design of the study, the researchers say. "Collecting oral tissue biopsies was essential in that it allowed us to learn that not only did the green tea extract appear to have benefit for some patients, but we pointed to anti-angiogenic effects as a potential mechanism of action," said Anne Tsao, M.D., assistant professor in the Department of Thoracic/Head and Neck Medical Oncology, and the study's first author. "While preliminary because our patient population was so small, this gives us direction for further study."

Of those taking green tea at the two highest doses, 58.8 percent had a clinical response, compared with 36.4 percent in the lowest extract dose and 18.2 percent in the placebo arm. At an extended follow-up with a mean of 27.5 months, 15 participants had developed oral cancer, with a median time to disease development of 46.4 months. Although not statistically significant, the green tea extract also improved histology and trended towards an improvement in a number of biomarkers that may play a vital role in predicting cancer development. Another important finding, say the researchers, was that that the extract was well tolerated. Side effects, including insomnia and nervousness, were mostly seen in the high-dose group but produced no significant toxicity.

"While these are encouraging findings, much more research must be done before we can conclude that green tea may prevent oral or any other type of cancer. It's also important to remind people that this trial enrolled very few participants who, at the highest dose levels took the equivalent of eight cups of green tea three times a day," said Papadimitrakopoulo. "We need to further understand if green tea offers longer-term prevention effects for patients." Papadimitrakopoulo and Tsao think that future studies with green tea in this high-risk population should focus on participants being exposed to the supplement for a longer time period. The researchers also stressed that the green tea extract studied in this trial was never sold over-the-counter and/or the Internet, both of which are not highly regulated. Rather, the compound was exclusively developed as a pharmaceutical.
According to the American Cancer Society, more than 35,720 are expected to be diagnosed with oral and/or pharynx cancer and the five year survival rate is less than 50 percent.

Source: University of Texas M. D. Anderson Cancer Center

[BACK2MYROOTS]

Ok, the results are not conclusive yet. But there is a link. That's good enough for me and for all green tea fans. So, where can you get some decent green tea for a reasonable price then? In a herbal shop? What about supermarket green tea, any good?

This is funny because not long ago, I threw away 2 boxes of green tea. They tasted awfully bitter, never as good as good old Algerian green tea [not to mention red tea, black tea etc.]. Does it go bitter when the packet is past the use by date?

How do you drink your tea anyway?
In a small glass or a large one?

And with or without fresh mint?

B2MR

[Al-khiyal]

A site that caters for real green tea connoisseurs who are based in the UK is >>> here <<<

[BACK2MYROOTS]

A site that caters for real green tea connoisseurs who are based in the UK is >>> here <<<

Thanks for the link Al-Khiyal, but the prices are extortionate! I'm going to have to go on a search campaign for Algerian green tea. Maybe I can get it in London, my son is there. I'll ask him. If anyone can point us to a particular shop, that would be very much appreciated.

Phew! I can't believe those prices.

Thanks again.

B2MR

[Al-khiyal]

Better prices at the Algerian Coffee Stores in London - but I don't know if they do Algerian green tea.

[Al-khiyal]

Green tea "may protect smokers from lung cancer" - study

LONDON, January 12, 201 (KUNA) -- Drinking green tea may help protect smokers from lung cancer, a study showed Tuesday. Scientists found smokers who drank at least one cup of the antioxidant-rich beverage a day were almost 13 times less likely to develop the disease than those who drank no green tea, the British media said. Among smokers and non-smokers combined, drinking green tea led to a more than five-fold reduced risk of lung cancer. The study was conducted in Taiwan, where people drink a lot of green tea.

Lead researcher I-Hsin Lin, from Chung Shan Medical University on the island, said: "Lung cancer is the leading cause of all cancer deaths in Taiwan. Tea, particularly green tea, has received a great deal of attention because tea polyphenols are strong antioxidants, and tea preparations have shown inhibitory activity against tumourigenesis".

Lin's team compared 170 lung cancer patients and 340 healthy individuals who were asked to provide information on their smoking habits, green tea consumption, diet, and family history. Participants were also tested for growth factors - biological chemicals - that stimulate cell growth, known to be associated with cancer. Green tea drinkers genetically predisposed to have less harmful growth factor variants were 66 percent less likely to develop lung cancer than tea drinkers with a more hazardous version.

"Our study may represent a clue that in the case of lung cancer, smoking-induced carcinogenesis could be modulated by green tea consumption and the growth factor environment," Lin was quoted by the media as saying. The findings were presented today at the Molecular Origins of Lung Cancer conference in Coronado, California. The meeting was jointly organised by the American Association for Cancer Research (AACR) and the International Association for the Study of Lung Cancer (IASLC).