Inclusion Criteria:

- Invasive ductal, medullary, papillary, colloid (mucinous), or tubular histologies;
invasive lobular carcinomas are allowed

- American Joint Committee for Cancer (AJCC) Stage IIa - IIIc (pathologic stage T0N1-3,
T1N1-3, T2N1-3, T3N0-3, T4N0-3, all M0 status) histologically confirmed invasive
carcinoma of the breast treated with mastectomy and either sentinel node biopsy or
axillary dissection; inflammatory carcinoma (T4d) is allowed

- Patients with locally advanced breast cancer on clinical exam and diagnostics ( > 3
cm and/or clinically node-positive) who have mastectomy after induction chemotherapy
are allowed

- Multifocal/multicentric disease is allowed

- Negative inked histologic margins of mastectomy (no invasive cells at margin) or
positive margin at pectoralis fascia or skin

- Tamoxifen, Arimidex or other hormonal therapy is allowed; it may begin any time
relative to the radiation at the discretion of the treating physician

- Chemotherapy is allowed, if chemotherapy is indicated the chemotherapy can be
delivered first, followed by radiation therapy beginning 21-63 days after the last
cycle of chemotherapy or the radiation therapy can be delivered first and the
chemotherapy can be delivered no earlier than 21 days post radiation therapy;
neoadjuvant chemotherapy is allowed; radiation therapy will be delivered after
mastectomy or after any adjuvant chemotherapy as described above

- Chest wall reconstruction is allowed

- The patient must be enrolled and have treatment planning between 14-63 days from date
of last surgery or last cycle of chemotherapy, and radiation must start within 21-63
days of date of last surgery or last cycle of chemotherapy

- Signed study-specific informed consent form prior to study entry

- Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

Exclusion Criteria:

- Patient with distant metastases (M1)

- Patients with ductal or lobular carcinoma in-situ alone (no invasive component) and
patients with non-epithelial breast malignancies such as sarcoma or lymphoma

- Patient with T1N0 or T2N0 disease

- Prior radiation therapy to the chest

- Patients with collagen vascular diseases, specifically systemic lupus erythematosus,
scleroderma, or dermatomyositis

- Patients with co-existing medical conditions with life expectancy < 2 years

- Patients with psychiatric (with the possible exception of incompetence as defined by
New Jersey [NJ] law) or addictive disorders that would preclude obtaining informed
consent

- Other malignancy, except non-melanomatous skin cancer, < 5 years prior to
participation in this study; the disease-free interval from any prior carcinoma must
be continuous

- Women who are pregnant or lactating due to potential exposure of the fetus to RT and
unknown effects of RT to lactating females

- Women who are able to conceive and unwilling to practice an effective method of birth
control; women of childbearing potential must have a negative urine or serum
pregnancy test within 7 days prior to treatment