The association of smoking with outcomes following breast cancer prognosis is not well understood. In a cohort study called Life After Cancer Epidemiology (LACE), 2,265 women diagnosed with breast cancer were followed for a median of 12 years. We used multivariable proportional-hazards models to determine whether smoking, assessed approximately two years post-diagnosis, was associated with risk of death among these women. We also undertook a systematic review of all cohort studies to date that have examined the association between smoking and breast cancer mortality. Compared with never smokers, women who were current smokers had a twofold higher rate of dying from breast cancer [hazard ratio (HR) = 2.01, 95 % confidence interval (CI) 1.27-3.18] and an approximately fourfold higher rate of dying from competing (non-breast cancer) causes (HR = 3.84, 95 % CI 2.50-5.89). Among seven studies that met the inclusion criteria in the systematic review, three studies and our own reported significantly increased risk of breast cancer death with current smoking. We found little evidence of an association between former smoking and breast cancer mortality (HR = 1.24, 95 % CI 0.94-1.64). Consistent with findings from our prospective observational study, the systematic review of seven additional studies indicates positive association of current smoking with breast cancer mortality, but weak association with former smoking. Women who smoke following breast cancer diagnosis and treatment are at higher risk of death both from breast cancer and other causes.

Objectives

We examined the association between comorbidity and long-term mortality from breast cancer and other causes among African-American and white women with breast cancer.

Methods

A total of 170 African-American and 829 white women aged 40-84years were followed for up to 28years with median follow-up of 11.3years in the Health and Functioning in Women (HFW) study. The impact of the Charlson Comorbidity Score (CCS) in the first few months following breast cancer diagnosis on the risk of mortality from breast cancer and other causes was examined using extended Cox models.

Results

Median follow-up was significantly shorter for African-American women than their white counterparts (median 8.5years vs. 12.3years). Compared to white women, African-American women had significantly fewer years of education, greater body mass index, were more likely to have functional limitations and later stage at breast cancer diagnosis, and fewer had adequate financial resources (all P<0.05). Proportionately more African-American women died of breast cancer than white women (37.1% vs. 31.4%, P=0.15). A positive and statistically significant time-varying effect of the Charlson Comorbidity Score (CCS) on other-cause mortality persisted throughout the first 5years of follow-up (P<0.001) but not for its remainder.

Conclusions

Higher CCS was associated with increased risk of other-cause mortality, but not breast cancer specific mortality; the association did not differ among African-American and white women.

The association of smoking with outcomes following breast cancer prognosis is not well understood. In a cohort study called Life After Cancer Epidemiology (LACE), 2,265 women diagnosed with breast cancer were followed for a median of 12 years. We used multivariable proportional-hazards models to determine whether smoking, assessed approximately two years post-diagnosis, was associated with risk of death among these women. We also undertook a systematic review of all cohort studies to date that have examined the association between smoking and breast cancer mortality. Compared with never smokers, women who were current smokers had a twofold higher rate of dying from breast cancer [hazard ratio (HR) = 2.01, 95 % confidence interval (CI) 1.27-3.18] and an approximately fourfold higher rate of dying from competing (non-breast cancer) causes (HR = 3.84, 95 % CI 2.50-5.89). Among seven studies that met the inclusion criteria in the systematic review, three studies and our own reported significantly increased risk of breast cancer death with current smoking. We found little evidence of an association between former smoking and breast cancer mortality (HR = 1.24, 95 % CI 0.94-1.64). Consistent with findings from our prospective observational study, the systematic review of seven additional studies indicates positive association of current smoking with breast cancer mortality, but weak association with former smoking. Women who smoke following breast cancer diagnosis and treatment are at higher risk of death both from breast cancer and other causes.