OneMark Device for Breast Cancer Surgery and Surveillance

Inclusion Criteria: * Provision of signed and dated informed consent form. * Stated willingness to comply with all study procedures and availability for the duration of the study. * Age ≥ 18 years. * In good general health as evidenced by medical history. * Deemed able to undergo general anesthesia for surgical resection. * For individuals who are capable of menstruating: must be post-menopausal, defined as no menses in the 12 months before enrollment or age \> 60 years. No additional requirements - besides the age requirement in inclusion criterion # 3 - are needed for individuals who are not capable of menstruating. For surgery cohort only: * Male and female patients with stage T1/T2 breast cancer visible by ultrasound. For surveillance cohort only: * Male and female patients with abnormal mammogram Breast Imaging Reporting and Data System (BI-RADS) category 4 or 5. * Ultrasound visible unifocal breast tumor \< 5 cm in diameter. * Low density tissue by mammogram either category A (fatty replaced) or category B (scattered densities); or high density tissue by mammogram either category C (heterogeneously dense) or category D (extremely dense). Exclusion Criteria: * Pregnancy or lactation. * Known allergic reactions to components of OneMark System or SAVI SCOUT. * Feverish illness within 7 days of placement of the device. * Previous treatment with another investigational drug or other intervention within 1 month of enrollment. * Previous use of neoadjuvant chemotherapy within 6 months of enrollment.