Inclusion Criteria:

- Low risk of multifocal disease within the breast whose tumor location is favorable
for brachytherapy catheter placement

- Diagnosis of invasive breast carcinoma (biopsy or fine needle aspiration cytology)
and be clinical stage T1N0 (primary tumor < 2cm, clinically negative nodes)

- Location of primary tumor is not immediately adjacent to the nipple of chest wall

- No evidence of two or more separate tumors within the breast

- All histologic types and pathologic grades of primary tumor

- No extensive intraductal component (substantial intraductal carcinoma away from the
primary tumor location)

- No lymphatic or vascular invasion

- Lymph node staging by sentinel node excision or axillary dissection confirms node
negative status (If node positive, implant is used to deliver boost to tumor bed)

- Assessment of final surgical margins should be predominantly negative, but a single
small region of focal positivity is allowable as it is for whole breast radiation

- 18 years of age or older

Exclusion Criteria:

- Tumor is too close to the chest wall to allow placement of catheters

- Contraindications to radiation therapy are present, including a history of
scleroderma, systemic lupus or other active connective tissue disease, pregnancy, or
prior chest wall radiation