Women with breast cancer who smoke regularly or used to be regular smokers have a significantly higher chance of faster breast cancer progression and dying from the disease, compared to non-smoking patients, researchers from the University of California, San Francisco revealed at the Ninth Annual AACR (American Association For Cancer Research) Frontiers in Cancer Prevention Research Conference. They carried out a large prospective cohort study involving women with breast cancer from several different ethnic groups.
Dejana Braithwaite, Ph.D., said:
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.
Braithwaite explained that a link between smoking and several cancers, including lung cancer has long been established, nobody was completely sure what impact it might have on breast cancer.
Specifically, it is unclear how long women live following breast cancer diagnosis and whether smoking increases the risk of death because of breast cancer progression or whether there is an association between smoking and life expectancy following breast cancer diagnosis that works through affecting non-breast cancer causes of death.
So, Braithwaite and team decided to find out whether any link existed between smoking and breast cancer mortality, as well as smoking’s other causes of death among females.
2,265 women from several different ethnic backgrounds were enrolled; between 1997 and 2000 all of them had been diagnosed with breast cancer. Follow-up on the participants continued for approximately nine years average. The investigators wanted to determine whether smoking had an impact on their risk of death from breast cancer, other causes, and all causes.
During the nine-year follow up 164 of the participants died from breast cancer while 120 died from other causes, the researchers reported.
Participants who regularly smoked at the time or used to be regular smokers were found to have twice the risk of dying from something else (not breast cancer) compared to the lifetime non-smokers.
They also tried to find out whether other factors might have a impact on risk, and analyzed the women’s BMI (body mass index), menopausal status, and molecular breast cancer subtype.
They found that:
- Women with HER1-negative tumor subtype were 61% more likely to die from breast cancer if they were current or past regular smokers compared to those who had never smoked.
- Women whose BMI was under 25 and smoked were 83% more likely to die from breast cancer compared to lifetime non-smokers of the same BMI
- Postmenopausal women who currently smoked regularly or used to had a 47% higher risk of dying from breast cancer compared to similar women who had 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.