Inclusion Criteria

DISEASE CHARACTERISTICS:

- Upon clinical exam and pre-operative imaging by MRI and mammogram both, two or three
foci of biopsy-proven breast cancer separated by ≥ 3 cm of normal breast tissue on
clinical exam and preoperative imaging; foci must include at least one focus of
invasive breast carcinoma with another focus of either invasive breast carcinoma or
ductal carcinoma in situ (DCIS); no more than 2 quadrants with biopsy-positive breast
cancer

- Ultrasound cannot be used to determine patient eligibility; eligibility to be
determined by bilateral mammogram and MRI only

- Bilateral mammogram ≤ 60 days prior to registration

- Bilateral breast MRI ≤ 45 days prior to registration

- cN0 or cN1 disease

- No cNX, cN2, or cN3 disease

- Willing to provide tissue samples for correlative research purposes

- Largest single focus of disease > 5 cm by either mammogram or MRI or both
(measurement of the largest single focus should include any satellite lesions within
1 cm of the index lesion)

- No clinical or radiographic evidence of metastatic disease

- No prior or current lobular carcinoma in situ (LCIS), DCIS, or invasive breast cancer
in the opposite breast (i.e., bilateral disease is not allowed)

- No patients with known BRCA mutations

PATIENT CHARACTERISTICS:

- Life expectancy of at least 5 years, excluding diagnosis of breast cancer (comorbid
conditions should be taken into consideration, but breast cancer diagnosis is not a
consideration)

- Men are excluded from this study

- Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0, 1, or 2

- Hemoglobin (Hgb) ≥ 8 g/dL

- Peripheral platelet count (PLT) ≥ 50,000/mm³

- Ability to complete questionnaire(s) by themselves or with assistance

- Willing to return to enrolling institution for follow-up during the Active Monitoring
Phase (the active treatment and observation portions) of the study

- Negative serum or urine pregnancy test done ≤ 7 days prior to registration, for women
of childbearing potential only

- None of the following:

- Pregnant women

- Nursing women

- Women of childbearing potential who are unwilling to employ adequate
contraception (as determined by the treating physician)

- No co-morbid systemic illnesses or other severe concurrent disease which, in the
judgment of the investigator, would interfere significantly with whole-breast
irradiation (such as connective tissue disorders, lupus, or scleroderma)

- No uncontrolled intercurrent illness including, but not limited to, ongoing or active
infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac
arrhythmia, or psychiatric illness/social situations that would limit compliance with
study requirements

- No other active malignancy ≤ 5 years prior to registration; EXCEPTIONS: non-melanotic
skin cancer or carcinoma-in-situ of the cervix

- If there is a history of prior malignancy, they must not be receiving other
specific treatment for their cancer

PRIOR CONCURRENT THERAPY:

- No surgical axillary staging procedure prior to study entry

- Fine-needle aspiration (FNA) or core-needle biopsy of axillary node is permitted

- No breast implants at time of diagnosis

- Patients who have had implants previously removed prior to diagnosis are
eligible

- No treatment including radiation therapy, chemotherapy, biotherapy, or hormonal
therapy for this cancer prior to registration

- No neoadjuvant endocrine therapy or neoadjuvant hormonal therapy

- No planned partial-breast radiation

- No administration of any investigational agent ≤ 30 days prior to registration