Importance: There are limited data about how lifestyle factors are associated with breast cancer prognosis among Black or African American women because most of the evidence is based on studies of White breast cancer survivors.
Objective: To examine the association of prediagnostic cigarette smoking and alcohol consumption with all-cause mortality and breast cancer-specific mortality in a cohort of Black breast cancer survivors.
Design, setting, and participants: This population-based cohort study included 1926 Black or African American breast cancer survivors who received a diagnosis from June 6, 2005, to May 21, 2019, identified in 10 counties in New Jersey through rapid case ascertainment by the New Jersey State Cancer Registry. Statistical analysis was conducted from January 1, 2021, to August 1, 2022.
Exposures: Information on prediagnostic cigarette smoking, alcohol consumption, and additional covariates was collected during in-person interviews. The covariates examined included smoking status at the time of breast cancer diagnosis (currently smoking at the time of breast cancer diagnosis, formerly smoking, or never smoking), smoking duration (number of years smoking), smoking intensity (cigarettes smoked per day), number of pack-years of smoking, and regular alcohol consumption the year before diagnosis (categorized as nondrinkers, ≤3 drinks per week, or >3 drinks per week).
Main outcomes and measures: Primary outcomes included breast cancer-specific mortality and all-cause mortality.
Results: Among the 1926 women in the study, the mean (SD) age at breast cancer diagnosis was 54.4 (10.8) years. During 13 464 person-years of follow-up (median follow-up, 6.7 years [range, 0.5-16.0 years]), there were 337 deaths, of which 187 (55.5%) were breast cancer related. Compared with never smokers, current smokers at the time of breast cancer diagnosis had a 52% increased risk for all-cause mortality (hazard ratio [HR], 1.52; 95% CI, 1.15-2.02), which was most pronounced for those with 10 or more pack-years of smoking (HR, 1.84; 95% CI, 1.34-2.53). Similar findings were observed for breast cancer-specific mortality (current smokers vs never smokers: HR, 1.27; 95% CI, 0.87-1.85), although they were not statistically significant. There was no statistically significant association between alcohol consumption and all-cause mortality (>3 drinks per week vs nondrinkers: HR, 1.05; 95% CI, 0.73-1.51) or breast cancer-specific mortality (>3 drinks per week vs nondrinkers: HR, 1.06; 95% CI, 0.67-1.67).
Conclusions and relevance: This population-based cohort study of Black breast cancer survivors suggests that current smoking at the time of diagnosis was associated with an increased risk of all-cause mortality, particularly among women with greater pack-years of smoking.