Association of smoking intensity with survival in patients with breast cancer

Background: Female breast cancer patients who smoke may have shortened survival compared to those who don't smoke. However, little is known about the effect of smoking intensity on survival of breast cancer patient smokers.

Methods: Data were obtained from 1996-2007 linkage of the Florida Cancer Data System Registry with the Florida Agency for Health Care Administration database. Our sample included female ≥18 years old, diagnosed with breast cancer, and residing in the state of Florida (n=127,754). Smoking intensity was defined by self-reported <1, 1-2, or >2 packs of cigarettes/day. To analyze the association between smoking intensity and survival, we performed univariate and multivariate Cox regression models. The multivariate models were adjusted with demographics; stage, grade, and histology of the tumor; hormonal status; treatments; and 31 comorbidities.

Results: The majority of the sample was White (90%), non-Hispanic (90%), and had a localized tumor (59%). In the univariate analysis, compared with never smoked, worse survival was seen for those who smoked 1-2 packs/day (hazard ratio [HR] 1.18; P<.001) and >2 packs/day (HR 1.69; P<.001). In the multivariate analysis, those who smoked 1-2 packs/day (hazard ratio [HR] 1.10; P<.001) and >2 packs/day (HR 1.40; P<.001) had worse survival compared with never smoked. Conclusion: Taking considerable confounders into account, smoking is associated with worse survival in female breast cancer patients; this effect is exacerbated with increased smoking intensity. Breast cancer patients who self-report smoking should be encouraged to quit or cut back. Smoking cessation strategies and education should be provided to these patients.