Background: Cigarette smoke has been found to affect the metastatic potential of tumor cells and stimulate angiogenesis but its effect on survival among women diagnosed with breast cancer remains poorly understood.

Methods: In a cohort of 2265 multiethnic women diagnosed with breast cancer between 1997 and 2000 and followed for the median of 9 years, we examined whether smoking affected death from breast cancer, non-breast cancer-related causes and all causes. Proportional-hazards models were used to determine whether smoking was associated with time to death while taking into account baseline age, education, body mass index, tumor characteristics and adjuvant treatment. All statistical tests were two-sided.

Results: There were 164 deaths from breast cancer and 120 deaths from non-breast cancer causes during the median follow up of 9 years. Compared with never smokers, women who were current or past smokers had a 39% higher rate of dying from breast cancer [hazard ratio (HR)=1.39, 95% confidence interval (CI) 1.05-1.84] and a two-fold higher rate of dying from competing (non-breast cancer) causes (HR=2.16, 95%CI 1.57-3.00). Subgroup analyses revealed that the adverse effect of smoking on breast cancer survival was highest among women with HER2 negative tumors (HR=1.61, 95%CI 1.12-2.32), body mass index of <25kg/m2 (HR=1.83, 95%CI 1.10-3.04) and postmenopausal status (HR=1.47, 95%CI 1.08-1.99).

Conclusions: In this prospective cohort study, smoking was associated with an important increased in the risk of death from all causes, competing and breast cancer-specific causes independently of clinical, sociodemographic and other lifestyle-related factors. Molecular breast cancer subtype, body mass index and menopausal status modified the effect of smoking on breast cancer-specific survival.

Citation Information: Cancer Prev Res 2010;3(12 Suppl):B88.

Copyright © 2010, American Association for Cancer Research
2010