Intensity Modulated Radiation Therapy or 3-Dimensional Conformal Radiation Therapy in Treating Patients With Lymph-Node Positive Breast Cancer

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