Jan. 17, 2010— -- Green tea may reduce the risk of lung cancer, particularly for smokers, according to a study released this week.
At least a cup a day was associated with more than 5-fold lower lung cancer risk among Taiwanese adults, reported I-Hsin Lin, of the Chung Shan Medical University in Zhonghe City, Taiwan, and colleagues.
Moreover, for current and former smokers, regular green tea intake was associated with a nearly 13-fold lower risk than abstaining from the drink, suggesting that the antioxidants in tea have "an inhibitory effect...elicited by smoking," the researchers said.
These findings were reported at the American Association for Cancer Research-International Association for the Study of Lung Cancer Joint Conference on Molecular Origins of Lung Cancer.
"We suggest smokers or nonsmokers, both of them, should drink green tea to keep away from lung cancer," Lin told MedPage Today. "However, the cessation of smoking is the best way for cancer prevention."
Indeed, preventing cancer with green tea is appealing, but it's too soon for a clinical recommendation, said Dr. Roy Herbst of the M.D. Anderson Cancer Center in Houston, Tex., and a chair of the conference.
"It should probably be the basis of a hypothesis for a larger chemoprevention trial across multiple populations," he said in an interview.
Given inconclusive results in prior studies, Lin's group designed a hospital-based study that included questionnaires and genetic typing of 170 lung cancer patients and 340 healthy controls of the same age and gender composition as the experimental group who presented for physical check-ups.
Most participants in both groups reported drinking no green tea. But seven of the 170 cases and 64 of the 340 controls said they typically drank at least one four-ounce cup per day.
Overall, lung cancer risk appeared linked to green tea consumption.
Compared with those who drank one or more cups per day, those who drank it infrequently (less than once a day) were 4.22 times more likely to develop lung cancer.
Those who didn't drink green tea at all were at 5.16-fold greater risk, nearly the same elevation in risk seen with smoking for 40 pack-years compared with never smoking.
Among those who had never smoked, greater green tea intake was more protective. But risk was not significantly lower for those who drank at least one cup daily versus those who drank none at all.
Among those who were currently smoking or who had ever smoked, non-tea drinkers had 12.71 times higher risk and those who had less than one cup a day were at 12.22 times greater risk of lung cancer than individuals who averaged one or more cups daily.
A long-term green tea habit appeared more protective as well, with a more than threefold reduction in risk for more than 10 years compared with none among both smokers and never smokers.
That green tea impacted smokers more than nonsmokers was a surprise, Lin said. She cautioned, though, that the study may have been confounded by various unmeasured factors. For example, since the control group was recruited at presentation for routine physicals, they may have followed a generally healthier lifestyle than those with lung cancer, Lin suggested.