But it may be too soon to count on a cup of green tea to curb lung cancer. So far, the scientists have only tested green tea extract against human lung cancer cells in test tubes, not people.

The researchers included Qing-Yi Lu, PhD, of the Center for Human Nutrition at the University of California at Los Angeles (UCLA).

Lu and colleagues exposed a sample of human lung cancer cells to a decaffeinated green tea extract. The lung cancer cells marinated in the green tea extract for up to three days.

The green tea extract remodeled a certain protein in the lung cancer cells. As a result, the lung cancer cells became more likely to stick together and less likely to move, the study shows.

Antioxidants in green tea may have tweaked the cancer cell protein, but it's not clear whether one antioxidant deserves all the credit or whether several antioxidants worked together, the researchers note.

The study doesn't prove that drinking green tea curbs lung cancer in people.

However, it may be possible to make new lung cancer drugs based on green tea extract, Lu's team suggests. Such drugs would target the lung cancer protein remodeled by the green tea extract in the lab tests.