Researchers will compare the breath profiles of women with breast cancer and those without to determine whether there are disease-specific patterns that can be leveraged to facilitate breast cancer detection.

Women with mammogram-confirmed breast tissue density undergoing standard-of-care breast cancer screening will be invited to participate. Those who provide informed consent will provide one breath sample and fill out a questionnaire about their medical history with help from the research coordinators. Breath samples will be collected prior to standard of care biopsy or MRI, and patients will be stratified into the case or control group based on their test results.

The primary goal of this project is to use exhaled alveolar breath and the subsequent spectral data produced by Breathe BioMedical's cavity ring-down spectrometer to further develop Breathe BioMedical's technology and machine learning algorithms to determine the feasibility of detecting breast cancer in women aged 40 to 74.

Secondarily, this project aims to identify patterns of VOCs that are either over- or under-represented in participants with breast cancer when compared to the breath profiles of participants without breast cancer. This project will also assess performance characteristics of the technology (e.g. sensitivity, specificity, false negative rate, and false positive rate) including subgroup analyses. This project aims to understand intra-subject variability by exploring differences in breath signatures before and after definitive management of breast cancer, including surgical resection.

Inclusion Criteria:

• Female (sex as assigned at birth);
• Aged 40 - 74 years;
• Mammography confirmed breast tissue density (BI-RADS density score of A, B, C or D);
• Scheduled for standard of care biopsy or MRI;
• Fluent in language of consent (English, Spanish, or French);
• Ability to give informed consent;
• Able to provide a breath sample.

Exclusion Criteria:

• Prior history of breast cancer;
• Previous surgical biopsy or surgical excision of breast cancer in the past six months;
• History of cancer (except basal cell or squamous cell carcinoma of the skin) in the past year;
• Acute respiratory infection and/or symptoms in the past seven days;
• MRI BI-RADS 3 undergoing active surveillance (MRI requiring six-month follow-up).
• Pregnant or become pregnant during the study.

The target population will be women aged 40-74. Women who are scheduled for standard of care breast biopsy or MRI will be recruited, and breath will be collected prior to breast biopsy or MRI. Those with biopsy-proven primary breast cancer will be assigned to the case cohort (true positives). Subjects in this cohort who are proceeding to breast surgery at Mayo Clinic Florida or Duke University will be screened to provide a second breath sample, 6 months after the completion of treatment. To be eligible for the control cohort, subjects must have a negative MRI (for surveillance or diagnostic purposes with BI-RADS 1 or 2) that confirms the absence of breast cancer (true negatives). Individuals who have received an MRI up to 8 weeks prior to breath sample collection may be approached, granted inclusion and exclusion criteria are met. Subjects will be recruited from participating clinical centers in Canada and the United States.