Active and passive cigarette smoke and breast cancer survival.

Purpose: The association between active and passive cigarette smoking before breast cancer diagnosis and survival was investigated among a cohort of invasive breast cancer cases (n = 1273) participating in a population-based case-control study.

Methods: Participants diagnosed with a first primary breast cancer between August 1, 1996, and July 31, 1997, were followed-up until December 31, 2002, for all-cause mortality (n = 188 deaths), including breast cancer-specific mortality (n = 111), as reported to the National Death Index.

Results: In Cox models, the adjusted hazards ratios (HRs) for all-cause mortality were slightly higher among current and former active smokers, compared with never smokers (HR, 1.23; 95% confidence interval [95% CI], 0.83-1.84) and 1.19 (95% CI, 0.85-1.66), respectively). No association was found between active or passive smoking and breast cancer-specific mortality. All-cause and breast cancer-specific mortality was higher among active smokers who were postmenopausal (HR, 1.64; 95% CI, 1.03-2.60 and HR, 1.45; 95% CI, 0.78-2.70, respectively) or obese at diagnosis (HR, 2.10; 95% CI, 1.03-4.27 and HR, 1.97; 95% CI, 0.89-4.36, respectively). Associations between smoking and all-cause and breast cancer-specific mortality did not differ by cancer treatment.

Conclusions: These data do not provide strong evidence for an association between smoking and all-cause or breast cancer-specific mortality, although smokers who are postmenopausal or obese at diagnosis may be at higher risk.