Lung cancer is the leading cause of cancer deaths among women, with most cases linked to smoking. But not everyone who gets lung cancer smokes. Indeed, among nonsmokers, lung cancer is still the seventh most-common cause of cancer worldwide. Most of the lung cancer cases among nonsmokers are in women.
Researchers now have some clues about this mysterious connection. In a study presented earlier this week at the annual meeting of the American Assn. for Cancer Research, scientists found that smoke triggers changes in gene expression in the lungs of female mice. That's not surprising. But those changes include increasing the activity of genes involved in estrogen metabolism. Based on these data, the study's authors suggest that estrogen metabolism (the process by which estrogen becomes available for use) may contribute to lung cancer in nonsmoking women as well.
The researchers, at Fox Chase Cancer Center in Philadelphia, found 10 genes were expressed in the lungs of female mice exposed to smoke. The gene most affected by smoke was one that is a key enzyme for estrogen metabolism.
It's possible that estrogen plays a role in lung cancer in women in a similar way as it does in breast cancer. Other studies have shown women with lung cancer who take hormone replacement therapy (which replaces estrogen) have worse outcomes than do women who don't take hormone therapy.
— Shari Roan
Photo credit: Advanced Cell Technology Inc.