Burden of breast cancer attributable to secondhand smoke in North American women: A GBD 2023 analysis (1990-2023).

Abstract

e22568 Background: Breast cancer remains a leading cause of cancer-related morbidity and mortality among women. Secondhand smoke is a preventable environmental carcinogen, yet its contribution to the breast cancer burden in North America has not been well explored. This study assesses long-term trends in breast cancer burden attributable to secondhand smoke among North American women. Methods: Data from the Global Burden of Disease (GBD) 2023 study were used to evaluate the burden of breast cancer attributable to secondhand smoke among North American women from 1990-2023. Age-standardized death rates and disability-adjusted life years (DALYs) were the measures analyzed. Eligible countries were identified according to the United Nations classification. Temporal trends over the study period were assessed using Joinpoint regression analysis to calculate annual percent change (APC) and average annual percent change (AAPC), with corresponding 95% confidence intervals. Results: From 1990-2023, breast cancer death rates attributable to secondhand smoke among North American women declined significantly overall (AAPC -3.32%). Substantial reductions were observed in Canada (AAPC -4.07%) and the United States (AAPC -3.23%). Declining trends were also seen in Mexico, Panama, Costa Rica, and Greenland. In contrast, mortality increased in El Salvador (AAPC 1.25%), Guatemala (1.18%), and Nicaragua (0.57%). Over the same period, age-standardized DALYs showed a similar overall decline across North America (AAPC -3.37%), with marked reductions in Canada (-4.01%) and the United States (-3.30%). However, age-standardized DALYs increased in El Salvador (1.10%), Guatemala (1.06%), and Nicaragua (0.81%). Conclusions: This GBD 2023 analysis demonstrates a substantial decline in breast cancer mortality and DALYs attributable to secondhand smoke among North American women over the past three decades, with the most pronounced reductions observed in Canada and the United States. These trends likely reflect the cumulative impact of comprehensive smoke-free legislation, declining household tobacco exposure, improved public awareness, and advances in breast cancer screening and treatment. In contrast, the rising burden observed in El Salvador, Guatemala, and Nicaragua highlights persistent regional disparities within North America. These increases may be driven by weaker enforcement of smoke-free policies, continued indoor biomass and tobacco exposure, limited access to early detection, and constrained oncology care infrastructure. The divergence in trends underscores the unequal benefits of tobacco control and cancer prevention strategies across the continent. Strengthening smoke-free environments, particularly in domestic settings, alongside targeted public health interventions in high-burden countries, may further reduce preventable breast cancer morbidity and mortality.