GeneSearch™ BLN Assay has been voluntarily withdrawn from the US market.

This post-approval study is designed to determine the performance of the FDA-approved GeneSearch™ BLN Assay when compared to the site's standard of care permanent section histological evaluation, and when compared to more extensive histological evaluation when the assay is being used by clinicians to make surgical decisions on complete axillary dissections (ALND).

The primary objective of this clinical study is to gather data to estimate the positive predictive concordance (PPC) between the GeneSearch™ BLN Assay and histology as routinely practiced, i.e., routine H&E histology of sentinel lymph node(s) (SLN) and, when available, routine histology of non-sentinel axillary lymph nodes (ALN). This study will provide information on the assay that will augment the performance data gained in pre-market validation studies. In addition, with the assay being used for ALND decision-making, the metastatic status of the non-sentinel axillary nodes can be taken into account in the performance measures, i.e., if the patient's sentinel or non-sentinel nodes are histologically positive, the patient will be considered positive for the primary comparison to the assay results.

Inclusion Criteria:

• Pre-operatively established diagnosis of invasive carcinoma of the breast
• Scheduled for axillary sentinel lymph node dissection as per standard of care at the clinical site for newly diagnosed breast cancer patients
• Patients for whom the GeneSearch™ BLN Assay will be used intra-operatively to make a decision for an axillary lymph node dissection
• 18 years of age or older
• Female or male
• Willing and able to give informed consent to participate in the study

Exclusion Criteria:

• Previous diagnosis of lymphoma
• Subjects participating in other research studies that would interfere with their full participation in this study
• Patients and/or conditions with 'interfering substances' as listed in the IFU.
• Patients who have had any pre-operative treatment for breast cancer including neoadjuvant and/or hormonal intervention such as aromatase inhibitors or tamoxifen

Patients must have been diagnosed with carcinoma of the breast and be a candidate for lymph node surgery as per each site's standard of care. The patients may be female or male, at least 18 years old, and must meet study inclusion criteria described later in this protocol. Patients receiving pre-operative therapy for breast cancer, such as neoadjuvant therapy and/or hormonal intervention are not eligible to participate in this study.