Smoking escalates a woman's risk of dying from breast cancer by at least 25%, according to a study that also says women can eliminate that increase by quitting.
Smokers were 25% more likely than nonsmokers and ex-smokers to die of breast cancer, according to a recent American Cancer Society survey of 604,412 women who were initially free of cancer. After six years, 880 had died of the disease, which strikes one in eight U.S. women.
The risk grew with the number of cigarettes a woman smoked, culminating in a 75% greater risk among women who smoked two packs a day or more. Quitting would return a former smoker's risk to that of a lifelong nonsmoker, researchers said.
An estimated 46,000 women will die this year of breast cancer, the second-most common cancer killer among women.
Eugenia Calle, an epidemiologist who directed the American Cancer Society research, said the study does not suggest that smoking causes breast cancer. Instead, she said the increased risk may result from "poorer survival or delayed diagnosis."
"For example, smokers may have impaired immune systems, they may not obtain routine (mammograms), or smoking may cause a direct deleterious effect on survival," Calle said.