Green tea reduced the risk of lung cancer in smokers

Green Tea May Lower Lung Cancer Risk

Benefits seen for smokers, nonsmokers, those with certain genetic makeup

Antioxidants in green tea appear to significantly lower the risk for developing lung cancer among smokers and nonsmokers alike, new research from Taiwan reveals.

The study suggests that smokers and nonsmokers who consume a minimum of one cup of green tea per day appear to have a nearly 13-fold and fivefold lower risk, respectively, for developing lung cancer than smokers and nonsmokers who don’t drink any green tea.

“The health effect of green tea consumption could modify the risk of lung cancer, particularly among smokers,” said study author I-Hsin Lin, of Chung Shan Medical University in Taichung.

Lin and her team are scheduled to present their findings at a lung cancer conference this week in Coronado, Calif. The conference is sponsored by the American Association for Cancer Research and the International Association for the Study of Lung Cancer.

The observed protective effect seems to result from the strong “antioxidative property” of polyphenols found in green tea preparations.

To determine just how strong this effect might be, the authors assessed the dietary intake and lifestyle habits of 170 lung cancer patients and 340 healthy patients.

The participants completed questionnaires outlining their smoking histories, green tea consumption habits, fruit and vegetable intake, and cooking practices. Patients were also asked to note any family history of lung cancer.

Genetic testing was also conducted to assess which particular insulin-like growth factor genotype — among several — each participant possessed.

This analysis was considered crucial, given the author’s observation that, independent of green tea consumption, genetically determined hormonal differences can affect how quickly cancer cells spread, thereby predisposing people toward a greater or lesser general risk for developing lung cancer in the first place.

While emphasizing that both smoking and nonsmoking tea drinkers generally benefited from green tea consumption relative to non-tea drinkers, the team observed that tea drinkers with particular growth factor genotypes seemed to gain even more protection — as much as 66 percent greater protection compared with tea drinkers bearing a different genetic background.

The findings reflect solely upon the potential interplay of green tea, genetics and lung cancer risk, the researchers noted, leaving aside potential questions regarding black tea consumption.

“Our results suggest the potential health benefits of green tea consumption,” concluded Lin. “However, cigarette smoking can serve as an initiator and promoter of carcinogenesis, [so] cessation of smoking is the best way for cancer prevention.”

Dr. Norman Edelman, chief medical officer of the American Lung Association, emphatically agreed.

“First of all, this is not a new concept,” he observed. “The idea that various antioxidants are protective to the lung has been around for a while, and green tea is a powerful antioxidant. But for us to really know whether or not just one cup can have such an enormous effect, you really have to look at more data and all the other possibly confounding factors, such as whether patients are obese, whether they are leading otherwise healthy lives, that kind of thing.”

“Meanwhile, what the American Lung Association is really afraid of,” cautioned Edelman, “is that people will look at this and think, ‘Oh, well, I can smoke as long as I have a few cups of green tea.’ Nothing could be further from the truth. Smoking is extremely toxic, obviously, and extremely detrimental to your health. And nothing changes this fact. So the most important thing here is that we don’t want anyone to get the message that it’s OK to smoke so long as I drink green tea.”

Meanwhile, another group reported that a diet high in leafy green vegetables, folate and some multivitamins might protect against smoking-related genetic changes that lead to lung cancer.

The researchers from Lovelace Respiratory Research Institute in Albuquerque, N.M., found those substances, including vitamins C, A and K, could influence a chemical modification called cellular gene methylation. Aberrant gene methylation is known to be a mechanism in the development of cancer in smokers.

Their findings were published online Jan. 12 in Cancer Research.

Exploring yet another front in lung cancer science, a second study scheduled for release at the lung cancer conference suggests that lung cancer patients who are smokers seem better able than nonsmoking patients to tolerate higher — and presumably more effective — dosages of a standard chemotherapy treatment known as erlotinib.

The research team, from the Wake Forest University in Winston-Salem, N.C., found that while nonsmokers ultimately developed dangerously toxic side effects — such as rashes, diarrhea and/or dehydration — when placed on an average daily dose regimen of just 225 milligrams of erlotinib, smokers didn’t develop similarly problematic reactions until the daily average dosage reached 300 milligrams.

Green Tea Could Modify the Effect of Cigarette Smoking on Lung Cancer Risk

Drinking green tea could modulate the effect of smoking on lung cancer. Results of this hospital-based, randomized study conducted in Taiwan were presented at the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer, held here from Jan. 11-14, 2010.

“Lung cancer is the leading cause of all cancer deaths in Taiwan,” said I-Hsin Lin, M.S., a student at Chung Shan Medical University 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 tumorigenesis.”

However, previous studies of green tea have been inhibited by the flaws of the epidemiologic model with its inherent biases.

Lin and colleagues enrolled 170 patients with lung cancer and 340 healthy patients as controls. The researchers administered questionnaires to obtain demographic characteristics, cigarette smoking habits, green tea consumption, dietary intake of fruits and vegetables, cooking practices and family history of lung cancer. They also performed genotyping on insulin-like growth factors as polymorphisms on the following insulin-like growth factors: IGF1, IGF2 and IGFBP3, which have all been reported to be associated with cancer risk.

Among smokers and non-smokers, those who did not drink green tea had a 5.16-fold increased risk of lung cancer compared with those who drank at least one cup of green tea per day. Among smokers, those who did not drink green tea at all had a 12.71-fold increased risk of lung cancer compared with those who drank at least one cup of green tea per day.

Lin and colleagues suspect genetics may play a role in this risk differential. Green tea drinkers with non-susceptible IGF1 (CA)19/(CA)19 and (CA)19/X genotypes reported a 66 percent reduction in lung cancer risk as compared with green tea drinkers carrying the IGF1 X/X genotype.

Heavy smokers carrying susceptible IGF1, IGF2 and IGFBP3 genotypes also had a higher risk of lung cancer compared with nonsmokers carrying non-susceptible IGF1, IGF2 and IGFBP3 genotypes.

“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,” said Lin.

More information

For additional details on green tea and lung cancer prevention, visit the National Cancer Institute,

American Association for Cancer Research

SOURCES: I-Hsin Lin, M.S. student, Chung Shan Medical University, Taichung, Taiwan; Norman Edelman, M.D., chief medical officer, American Lung Association, Stonybrook, N.Y.; Jan. 11-14, 2010, presentations, AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer, Coronado, Calif.