Benefits seen for smokers, nonsmokers, those with certain genetic makeup
TUESDAY, Jan. 12 (HealthDay News) -- 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.
For additional details on green tea and lung cancer prevention, visit the National Cancer Institute.
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.
All rights reserved