Association between chronic bronchitis and increased breast cancer risk in female patients.

BACKGROUND: Respiratory diseases and breast cancer both pose significant threats to women's health, but the association between them remains unclear. METHODS: This analysis utilised data including 25,132 adult female participants. After adjusting variables, a logistic regression model assessed the association between respiratory diseases and breast cancer risk. We investigated the nonlinear dose-response relationship between pulmonary function tests and breast cancer, and analysed the association of pulmonary function test with breast cancer risk across different racial groups. We explored the heterogeneous characteristics of key metabolic and inflammatory markers in different groups. RESULTS: In the fully adjusted model, chronic bronchitis was associated with prevalent breast cancer. Restricted cubic spline curve revealed elevated breast cancer risk when pulmonary function test met the following thresholds: FEF25-75% < 2,405 ml/s, FEV1/FVC < 0.794, and FEV3/FVC < 0.926, with stronger associations between pulmonary function and breast cancer risk found among non-Hispanic whites and blacks. Serum lipid metabolism and inflammation markers showed significant elevation. CONCLUSION: Chronic bronchitis exhibits a potential correlation with breast cancer risk. In non-Hispanic whites and non-Hispanic blacks, declining pulmonary function may associate with increased breast cancer risk.