This phase II trial studies the shoulder morbidity in patients with lymph-node positive breast cancer receiving intensity modulated radiation therapy or 3-dimensional conformal radiation therapy. Intensity modulated radiation therapy may cause less shoulder/arm morbidity in patients with lymph-node positive breast cancer.

PRIMARY OBJECTIVES:

I. To determine if intensity modulated radiation therapy (IMRT) reduces average 1-year patient-reported shoulder/arm morbidity in women receiving regional nodal irradiation (RNI) for lymph-node positive breast cancer as compared to historical data.

SECONDARY OBJECTIVES:

I. To measure patient-reported shoulder/arm morbidity in women receiving RNI with 3-dimensional conformal radiation therapy (3DCRT) for lymph-node positive breast cancer.

II. To measure change in shoulder range of motion in women receiving RNI. III. To measures rates of ipsilateral upper extremity lymphedema in women receiving RNI.

IV. To explore the dose volume parameters to the shoulder/neck/trunk musculature associated with worsening patient-reported shoulder/arm morbidity.

V. To assess disease outcomes in patients treated with IMRT. VI. To measure long-term patient-reported shoulder/arm morbidity in women receiving RNI with IMRT or 3DCRT.

OUTLINE: Patients are assigned to 1 of 2 arms.

ARM A: Patients undergo IMRT over 5 weeks.

ARM B: Patients undergo 3DCRT over 5 weeks.

After completion study treatment, patients are followed up at 1, 6, and 12 months, and then annually for up to 5 years.

Inclusion Criteria:

• Pathologically proven diagnosis of breast cancer
• Patients that receive neoadjuvant systemic therapy (chemotherapy, anti-HER2 therapy, or endocrine therapy) are eligible
• History/physical examination within 60 days prior to study entry
• Patients who have undergone either a lumpectomy or mastectomy are eligible
• Patients that have undergone any type of breast reconstruction are eligible
• The interval between the date of last surgery or chemotherapy and registration must be =< 84 days
• Women of childbearing potential must have a negative urine or serum pregnancy test within 14 days of start of radiation therapy
• Women of childbearing potential must be non-pregnant and non-lactating and willing to use medically acceptable form of contraception during radiation therapy
• Patients must provide study specific informed consent prior to study entry

Exclusion Criteria:

• Clinical or radiologic evidence of distant metastases
• Patients with known unresected disease in the axillary apex or supraclavicular fossa
• Prior invasive or in-situ carcinoma of the breast (prior lobular breast carcinoma in situ [LCIS] is eligible)
• Prior surgery to the ipsilateral shoulder for any condition
• Baseline impaired mobility of the ipsilateral shoulder from a condition not related to the breast cancer surgery as determined by the treating physician
• Non-epithelial breast malignancies such as sarcoma/lymphoma
• Prior radiotherapy to the breast or prior radiation to the region of the ipsilateral breast that would result in overlap of radiation fields
• Medical, psychiatric, or other conditions that would prevent the patient from receiving the protocol therapy or providing informed consent
• Pregnancy or women of childbearing potential who are sexually active and not willing/able to use medically acceptable forms of contraception
• Active systemic lupus, erythematosus, or any history of scleroderma, dermatomyositis with active rash