Smoking before or after cancer diagnosis was associated with a higher mortality from breast cancer and several other causes, a study published online ahead of print in the Journal of Clinical Oncology has shown.1
Although cigarette smoking is known to increase overall mortality, whether smoking is associated with breast cancer prognosis is unclear. Therefore, researchers sought to evaluate the association between smoking status before and after diagnosis and mortality in the Collaborative Breast Cancer and Women’s Longevity Study, a population-based prospective observational study conducted in Massachusetts, New Hampshire, and Wisconsin.
Participants included 20 691 women age 20 to 70 years with a diagnosis of incidence localized or regional invasive breast cancer between 1988 and 2008. Of those, 4562 women were recontacted a median of 6 years following their cancer diagnosis.
Results showed that during a median follow-up of 12 years, 6778 women died, including 2893 due to breast cancer.
Researchers found that active cigarette smokers 1 year before diagnosis were more likely than never smokers to die of breast cancer (HR, 1.25; 95% CI: 1.13-1.37), respiratory cancer (HR, 14.48; 95% CI: 9.89-21.21), other respiratory disease (HR, 6.02; 95% CI: 4.55-7.97), and cardiovascular disease (HR, 2.08; 95% CI: 1.80-2.41).
The study further demonstrated that the 10% of women who continued smoking after diagnosis were more likely to die of breast cancer (HR, 1.72; 95% CI: 1.13-2.60) compared with never smokers.
Patients who quit smoking after diagnosis had a lower risk of death from breast cancer (HR, 0.67; 95% CI: 0.38-1.19) and respiratory cancer (HR, 0.39; 95% CI: 0.16-0.95) than those who continued to smoke after diagnosis.
1. Passarelli MN, Newcomb PA, Hampton JM, et al. Cigarette smoking before and after breast cancer diagnosis: Mortality from breast cancer and smoking-related diseases [published online ahead of print January 25, 2016]. J Clin Oncol. doi:10.1200/JCO.2015.63.9328.