Smoking and Breast Cancer Metastasis

A team of researchers from the University of California-Davis Medical Center has found that women with breast cancer who smoke face a significantly higher risk of their cancer spreading to the lungs.

Writing in the journal Chest, Dr. Susan Murin and John Inciardi, PharmaD. reported that women with breast cancer whose tumors had spread to the lungs were twice as likely to have been smokers compared to those whose cancer had not spread to the lungs. They based their findings on a study of 87 women whose invasive breast cancer had metastasized to the lungs and 174 women whose breast cancer had not spread.

They noted that their results back up previous research that has linked smoking to a higher risk of lung metastasis in women with breast cancer, and that women who smoke are more likely to die of breast cancer than non-smokers.

They acknowledged that the exact reason for cancer in smokers being more likely to spread to the lungs was unclear, but they speculated that cigarette smoke may make the lungs a more "fertile environment" for cancer.

"Smoking changes the immune function of the lungs and makes blood vessels more leaky," Murin said in an interview with the BBC. "Once cancer cells escape the bloodstream, they are more likely to set up housekeeping in distant sites."

Other factors, such as smokers tending to have less healthy diets and exercising less often, could also contribute to the link, she added.

An editorial published with the study suggests that smokers diagnosed with breast cancer should be offered support to help them stop smoking. Murin would certainly concur. "Women are more likely to survive breast cancer if they don't smoke," she said. "If we can let them know that, it might motivate some women to quit."

SOURCES:
Chest, June 2001; 119:1635-1640
BBC News (http://www.bbc.co.uk)

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