MONDAY, June 11, 2001 (HealthDayNews) -- Breast cancer patients who smoke are twice as likely as nonsmokers to develop much more deadly lung cancer, a new study says.
While smoking does not appear to increase the risk of breast cancer,
"the data suggest that breast cancer follows a more aggressive course among women who smoke," says study co-author Dr. Susan Murin, of the University of California at Davis. "The reasons for that haven't been teased out," she says.
Tobacco smoke damages the airways, compromising their ability to fight infection and their ability to destroy stray cancer cells that have broken away from the breast, Murin says. That may "make it more likely that any tumor cells that make it to the lungs will survive and cause disease there."
The findings are published in this month's issue of the journal Chest.
The American Cancer Society estimates that more than 193,000 American women will be diagnosed with breast cancer this year, and 40,000 will die from the disease.
Lung cancer, on the other hand, will kill four times as many people -- 157,000 of the 169,500 Americans who will get the disease this year, the society says.
Murin and colleague Dr. John Inciardi looked for the effect of smoking in 87 women with breast cancer that had spread to their lungs and 174 whose tumors were confined to their breasts.
Of the women with lung metastasis, 38 percent said they'd smoked in the past, compared with 29 percent of those with isolated cancer. Nearly a quarter of women with lung tumors said they were active smokers at the time their breast cancer was diagnosed, compared with only 15 percent of the women with only breast cancer.
After adjusting for factors, like age when breast cancer was diagnosed and the size of tumors, women who smoked at the time their breast tumors appeared were nearly twice as likely as nonsmokers or those who'd already quit to have the disease move into their lungs, the study says.
"You could argue that we don't need any more studies telling us that smoking's bad for you. Yet in spite of the general knowledge, there still are far too many people who are smoking," says Dr. Mhel Kavanaugh-Lynch, director of the Oakland-based California Breast Cancer Research Program.
Ironically, most women, and particularly young women, are much more afraid of breast cancer than they are of lung cancer, Kavanaugh-Lynch says. "This could provide stronger motivation for women not to smoke by speaking to something they're more afraid of. It has the potential to have far-reaching public health impact."
Murin is planning to study how smoking affects breast cancer cells in mice, including how long before breast cancer develops does exposure to the tumor-causing chemicals in tobacco have to stop to avoid metastisis.
Murin also will study whether heavier smokers are at increased risk of metastatic breast cancer. Earlier research found that smoking ups a woman's risk of dying from breast cancer by 25 percent and increases with the number of cigarettes smoked per day and the number of years a woman smoked. Women who smoked two packs a day or more have a 75 percent higher risk of death from breast cancer than nonsmokers, those studies found.
What To Do
Smoking is the leading cause of lung cancer. It has been linking to 80 percent of cases, so the best way to avoid the deadly disease is to quit or avoid starting the habit.
To learn more about lung cancer, try the Lung Cancer Awareness Campaign or the American Cancer Society.
For more on breast cancer, try the California Breast Cancer Research Program.
Visit Veritas Medicine to learn more about breast cancer and lung cancer.
