The risk of breast cancer progression and mortality in women was significantly increased by having a history of smoking or being a current smoker.
“We found that women who are current smokers or have history of smoking had a 39 percent higher rate of dying from breast cancer, even after we took into account a wide array of known prognostic factors including clinical, socioeconomic and behavioral factors,” said Dejana Braithwaite, Ph.D, assistant professor, division of cancer epidemiology, department of epidemiology and biostatistics at the University of California, San Francisco.
The specific effect of smoking on breast cancer has been unclear although smoking is associated with lung cancer and directly linked in several other cancers.
They enrolled 2,265 multi-ethnic women diagnosed with breast cancer between 1997 and 2000. The women were followed for an average of nine years and the results showed 164 deaths from breast cancer and 120 deaths from non breast cancer causes. Researchers examined whether smoking affected death from breast cancer, non-breast cancer related causes and death from all causes.
Those women who had a history of smoking or who were current smokers also had a twofold increased risk for dying from non-breast cancer related causes compared with women with breast cancer who had never smoked.
In addition women who were current or past smokers and also had a HER2-negative tumor subtype had a 61 percent increased risk for breast cancer death compared with those who never smoked. Smokers with a body mass index less than 25 kg/m2 had an 83 percent increased risk for breast cancer death, and postmenopausal women had a 47 percent increased risk for breast cancer death compared with those who never smoked.
“The implication of this research is that it is important for physicians to improve smoking cessation efforts, especially among women newly diagnosed with breast cancer, in order to improve breast cancer specific outcomes and overall health outcomes,” Braithwaite said.