Global trends and projections of tracheal, bronchial, and lung cancer (TBL) associated with secondhand smoke (SHS) exposure in women: insights of the Global Burden of Disease (GBD) study 2021 from 1990 to 2021 and prediction to 2035.

Background: Tracheal, bronchial, and lung cancer (TBL) is a leading cause of cancer-related deaths, with 2.5 million new cases globally in 2022-the highest incidence of any cancer. However, a comprehensive global analysis of the disease burden of TBL attributable to secondhand smoke (SHS) exposure among women is currently lacking. To address this gap, we used the most recent data from the Global Burden of Disease (GBD) 2021 study to assess the global, regional, and national burden from 1990 to 2021 across 204 countries and territories, to analyse temporal trends, and to project the potential trajectory up to 2035. Methods: The data have been sourced from the 2021 GBD study, which encompass specific health indicators across 204 countries and territories from 1990 to 2021. Utilising the analytical framework of frontier analysis, we sought to quantify the unrealised potential for disease burden reduction at equivalent development levels across nations. In addition, we identified the theoretically optimal performance frontier and employed decomposition analysis to evaluate the contribution of each influencing factor. Moreover, utilising this framework, a Bayesian age-period-cohort model was adopted for the scientific projection of the disease's trajectory through 2035. Results: In 2021, the number of deaths among women worldwide attributable to SHS exposure for TBL was 41,062.72 [95% uncertainty interval (UI): 5,535.86 to 78,059.16], with DALYs totalling 996,309.39 (95% UI: 1,359,881.8 to 1,907,078.95). The global burden of this disease was predominantly concentrated among women aged 50-80 years. Amongst the 204 countries and territories examined, China demonstrated the highest ASDR and ASDAR for TBL related to SHS exposure among women [2.50 per 100,000 population (95% UI: 0.34-4.80) and 59.78 per 100,000 population (95% UI: 8.19-114.91), respectively]. In the context of the five socio-demographic index (SDI) regions, the highest standardized death rate change was observed in the high-SDI region (-2.00; 95% confidence interval: -2.18 to -1.82). Furthermore, an increase in the burden of female TBL attributable to SHS exposure was noted as SDI levels rose. Conclusions: The global burden of TBL among women exposed to SHS is declining, with both ASDR and ASDAR falling between 1990 and 2021. Projections indicate a further reduction in deaths and DALYs by 2035. Nevertheless, SHS continues to be a significant public health concern, requiring enhanced global collaboration and targeted interventions to mitigate its adverse effects on women's health even further.