Jan. 12, 2010 (Coronado, Calif.) -- Drinking a cup or more a day of green tea may counteract the effect of smoking on lung cancer, especially in smokers who may not be genetically susceptible to the cancer, according to a Taiwanese researcher.
''The antioxidants may inhibit tumor growth," I-Hsin Lin, a master's degree student at Chung Shan Medical University in Taiwan, tells WebMD. She presented her findings today at the American Association of Cancer Research -- International Association for the Study of Lung Cancer meeting in Coronado, Calif.
Lin found the protective effect especially evident in a group of smokers she studied who have specific genotypes that have not been linked to cancer risk in some studies.
Lin's team evaluated 170 patients with lung cancer and 340 healthy patients. They asked the participants to describe their cigarette smoking habits, green tea drinking habits, and other lifestyle factors.
They asked participants to describe habits for the previous five years, Lin says.
The researchers performed genotyping in the participants to see if they had any of the genotypes found in some studies to be associated with cancer risk. These include IGF1 (insulin-like growth factor 1), IGF2, and IGFBP3.
Overall, the smokers and nonsmokers who didn't drink green tea had a more than five times greater risk of lung cancer compared to those who had at least a cup of green tea, Lin found.
Among the smokers, the non-green-tea drinkers had a nearly 13 times increased risk of lung cancer compared to the smokers who drank one cup or more of green tea per day.
Even more dramatic was the protective effect of the green tea in those who did not have the susceptible genotypes for lung cancer, the researchers found.
The green tea drinkers who didn't have a genotype termed by the researchers as susceptible had a 66% reduced risk in lung cancer compared to the green tea drinkers who were susceptible.
Those who smoked heavily and had the susceptible genotype had an even higher risk.
While Lin says the best way to avoid lung cancer is to stop smoking, green tea appears to reduce risk. "Green tea can protect them from lung cancer risk, a cup or more a day," she says.