Inclusion Criteria

Eligibility:

1. Histologically proven primary invasive breast carcinoma.

2. Tumor pathologically determined <= 5cm in diameter.

3. Single, discrete, well-defined primary tumor.

4. Any micro-calcifications must be focal. A specimen radiograph is required after
lumpectomy to assure removal of all malignant appearing calcifications.

5. Pathologically negative surgical margins.

6. Axillary lymph node status can be determined by level I and II lymph node dissection
or sentinel lymph node sampling.

7. ECOG performance status 0-2.

Contraindications:

1. Multicentric disease and/or diffuse malignant appearing microcalcifications.

2. Evidence of metastatic breast cancer.

3. Axillary lymph node involvement.

4. Pre-existing collagen vascular disease except rheumatoid arthritis that does not
require immunosuppressive therapy.

5. Prior irradiation to the ara of planned radiation field.

6. Pregnant or lactating women.