Inclusion Criteria:

- Patient must be female.

- Patient must be at least 18 years of age.

- Patient's clinical stage must be documented as tumor size less than 5 cm, with no
palpable nodes and no evidence of metastatic disease (T1 or T2 N0 M0)

- Patient must have a negative (normal) axillary ultrasound performed at Siteman Cancer
Center. Lymph nodes will be evaluated based on morphologic features. AUS wil be
considered positive (abnormal)if lymph nodes are noted to be completely hypoechoic
(absent hilum) or have focal hypoechoic cortical thickening/lobulation greater than 4
mm.

- Patient must have a tissue diagnosis of invasive breast carcinoma

- Patient must have Eastern Cooperative Oncology Group (ECOG) status documented in patient's medical record.

- Patient must be available for follow-up.

- A patient with a history of previous malignancy is eligible for this study as long as
the patient meets the following criteria for a cancer survivor. A cancer survivor is
eligible provided that the following criteria are met (1) The patient has undergone
potentially curative therapy for all prior malignancies; (2) There has been no
evidence of recurrence (except for effectively treated basal cell or squamous
carcinoma of the skin, carcinoma in-situ of the cervix that has been effectively
treated by surgery alone, or lobular carcinoma in-situ of the ipsilateral or
contralateral breast treated by surgery alone); and (3) The patient is deemed by
their treating physician to be at low riks for recurrence from prior malignancies.

- Patient, or the patient's legally acceptable representative, must provide a signed
and date written informed consent prior to registration and any study-related
procedures.

- Patient must provide written authorization to allow the use and disclosure of their
protected health information. NOTE: This may be obtained in either the
study-specific informed consent or in a separate authorization form and must be
obtained from the patient prior to study registration.

- Patient must be a candidate for sentinel lymph node biopsy (SLNB).

- Exclusion Criteria:

- Patient in lactating (breast-feeding) or pregnant.

- Patient has concurrent invasive bilateral breast malignancies or multicentric
disease.

- Patient has had previous ipsilateral axillary surgery such as excisional biopsy of
lymph nodes(s), treatment of hidradenitis.

- Patient is considered poor candidate surgical candidate due to non-malignant
systemic disease.

- Patient has undergone or plans to undergo neoadjuvant chemotherapy of endocrine
therapy.