The study will determine the sensitivity, specificity, negative predictive value and positive predictive value of the OSNA Breast Cancer System by comparing its performance to permanent section Hematoxylin and Eosin (H&E) and IHC staining.

Inclusion Criteria:

• Male or Female patients, over the age of 18, diagnosed pre-surgically with T1 or T2 breast cancer and scheduled for surgery including sentinel node dissection.
• Patients who have read and understand the informed consent form and are capable and willing to provide written informed consent.

Exclusion Criteria:

• Patients diagnosed pre-surgically with large or locally advanced (T3 and T4) breast cancers.
• Patients diagnosed with inflammatory breast cancer.
• Patients diagnosed with ductal carcinoma in situ (DCIS) when breast conserving is to be done.
• Patients who are pregnant, as confirmed by a patient/treating physician interview.
• Patients with suspicious palpable axillary lymph nodes.
• Patients currently being treated for or previously diagnosed with, another type of carcinoma.
• Patients who have undergone prior non-oncologic breast surgery or axillary surgery.
• Patients who have received pre-operative systemic therapy.
• Patients who are incapable of providing written informed consent.
• Patients who have been judged to be inappropriate by a medical care provider (i.e. surgeon, oncologist, pathologists, etc.).

Patients with a previous diagnosis of breast cancer scheduled for sentinel lymph node dissection.