Inclusion Criteria

Inclusion

- Patients with multicentric carcinoma (tumors in different quadrants of the breast or
tumors separated by at least 4 cm)

- All radiographically suspicious lesions must be biopsied and have histologically
confirmed ductal carcinoma in-situ, invasive ductal, invasive lobular, medullary,
papillary, colloid (mucinous), or tubular histologies

- A maximum of two radiographically detected malignant lesions

- Clinical Stage I-II breast carcinoma, with lesion size =< 5 cm for the dominant mass
and the second lesion detected only on MRI, treated with lumpectomies; the MRI
detected lesion must be pathologically =< 1 cm

- Axillary lymph node evaluation, either sentinel lymph node biopsy or axillary
dissection as deemed appropriate by the treating surgeon for all patients with
invasive cancer; no axillary lymph node sampling is needed for patients with DCIS

- Negative resection margins with at least a 2 mm margin from invasive and in-situ
cancer or a negative re-excision

- A posterior margin =< 2 mm from DCIS is permissible provided fascia was taken

- Patients are eligible regardless of estrogen receptor, progesterone receptor, or
Her-2/neu amplification

- Hormonal therapy is allowed; if adjuvant chemotherapy is planned, the chemotherapy
should be delivered first and radiation must begin no earlier than three weeks and no
later than eight weeks following completion of chemotherapy

- Signed study-specific informed consent prior to study entry

Exclusion

- Extensive intraductal component by the Harvard definition (i.e., more than 25% of the
invasive tumor is DCIS and DCIS present in adjacent breast tissue)

- Palpable or radiographically suspicious contralateral axillary, ipsilateral or
contralateral supraclavicular, infraclavicular, or internal mammary lymph nodes
unless these are histologically confirmed negative

- Patients receiving neoadjuvant chemotherapy

- Patients with distant metastatic disease detected by radiographic imaging; specific
studies for systemic imaging should be obtained as directed by localized symptoms or
per available NCCN guidelines

- Patients with known BRCA 1/BRCA 2 mutations or those with predicted risk of carrying
the mutation by BRCAPRO (44) risk assessment >= 50%

- Diffuse calcifications throughout the breast

- Patients with skin involvement or inflammatory breast cancer

- Patients with Paget's disease of the nipple

- Patients nonepithelial breast malignancies such as lymphoma or sarcoma

- Patients with collagen vascular disorders, specifically systemic lupus erythematosis,
scleroderma, or dermatomyositis

- Patients with psychiatric, neurologic, or addictive disorders that would preclude
obtaining informed consent

- Other malignancy, except non-melanomatous skin cancer, < 5 years prior to
participation in this study

- Patients who are pregnant or lactating, due to potential fetal exposure to radiation
and unknown effects of radiation on lactating females