Fig. 1

Patient Enrollment and Study Design. This multi-center cohort study consecutively recruited women who underwent breast cancer screening at six hospitals in China. The participants were divided into the discovery cohort to identify candidate VOCs and to construct diagnostic models, and the external validation cohorts to independently test the diagnostic value of the models. In the model construction, the discovery dataset was randomly split into training, internal validation, and test datasets with a ratio of 5:2:3. The external validation cohorts enrolled women who underwent opportunistic breast cancer screening at Yantai and Wenzhou and women underwent the population-based breast cancer screening at Guiyang. For each participant, the information of risk factors for breast cancer and breath sample was breath sample collected before the standard mammography and ultrasonography. The final diagnosis was based on the pathology result and a 6-month follow-up. 78 patients lost to follow-up were excluded. Abbreviation: BC, breast cancer; CAMS, Chinese Academy of Medical Sciences