Environmental Tobacco Smoke Exposure and Survival Following Breast Cancer
Menée aux Etats-Unis auprès de 1 508 patientes atteintes d'un cancer du sein diagnostiqué entre 1996 et 1997, cette étude évalue l'association entre une exposition au tabagisme passif, la mortalité spécifique et toutes causes confondues (durée de suivi : supérieure à 18 ans, 597 décès dont 237 décès par cancer du sein)
Background: Environmental tobacco smoke (ETS) exposure is hypothesized to influence survival after breast cancer, but few studies have examined this association.
Methods: A population-based cohort of women (N=1,508) diagnosed with first primary invasive or in situ breast cancer in 1996-1997 was interviewed shortly after diagnosis and again approximately 5 years later to assess ETS exposure, and women were followed for over 18 years using the National Death Index; 597 deaths (237 associated with breast cancer) were identified. Multivariable Cox regression was used to estimate adjusted hazard ratios (HR) and 95% confidence intervals (CI) for mortality among women with breast cancer as related to at-diagnosis and at-/post-diagnosis changes in ETS exposure.
Results: There was little or no association between at-diagnosis ETS exposure and all-cause (HR=1.04, 95% CI=0.78-1.40) or breast cancer-specific (HR=0.98, 95% CI=0.63-1.52) mortality. Mortality was elevated among women who reported cessation in post-diagnosis ETS exposure up to one year before the follow-up assessment, for all-cause (HR=1.81, 95% CI=0.87-3.74) and breast cancer mortality (HR=1.89, 95% CI=0.68-5.24); however, estimates were imprecise.
Conclusions: We found little evidence of an association between at-diagnosis ETS exposure and mortality after breast cancer. Post-diagnosis cessation of ETS exposure was positively associated with mortality, although we could not rule out chance and reverse causation as possible explanations.
Impact: Exposure to ETS does not appear to influence mortality after breast cancer.
Cancer Epidemiology Biomarkers & Prevention , résumé, 2015