Patients with a prior diagnosis of contralateral ductal carcinoma in situ (DCIS) are eligible if they underwent a mastectomy or lumpectomy with whole breast radiation; prior partial breast irradiation, including brachytherapy, is not allowed; patients with a prior diagnosis of ipsilateral DCIS or invasive breast cancer who received radiation to that breast are not eligible
Patients must have had either breast-conserving surgery with planned radiation therapy or total mastectomy (with or without planned postmastectomy radiation); patients must have clear margins from both invasive breast cancer and DCIS (as per local institutional guidelines); lobular carcinoma in situ (LCIS) at the margins is allowed
Patients may be registered AFTER surgery and PRIOR TO radiation therapy if either of the criteria is met:* An area of atypia > 2 cm from the index lesion excised at the time of cancer operation is upgraded to DCIS or invasive carcinoma thereby identifying MIBC OR* Patient underwent resection of two or three foci of malignancy by breast conservation surgery with a minimum of one invasive focus of breast cancer and a minimum of 2 cm of normal breast tissue between the lesions on final pathology
Prior history of ipsilateral breast cancer (DCIS, LCIS [lobular cancer in situ] or invasive)
Prior or current LCIS, DCIS or invasive breast cancer in the opposite breast (i.e., bilateral disease is not allowed)
No patients with previous ipsilateral or contralateral invasive breast cancer or ductal carcinoma in situ (DCIS)
Synchronous or previous contralateral invasive breast cancer or DCIS; (patients with synchronous and/or previous contralateral LCIS are eligible)
Any prior history, not including the index cancer, of ipsilateral invasive breast cancer or ipsilateral DCIS treated with radiation therapy; (patients with synchronous or previous ipsilateral LCIS are eligible)
No prior history of ipsilateral breast cancer (invasive disease or ductal carcinoma in situ [DCIS]); lobular carcinoma in situ (LCIS) and benign breast disease is allowed
No history of prior or concurrent contralateral invasive breast cancer; benign breast disease; LCIS or DCIS of contralateral breast is allowed
For those patients who also undergo contralateral breast surgery, if invasive disease is found in the contralateral breast, the patient is not eligible for registration /randomization
Documentation of mammogram and ultrasound (including ductal carcinoma in situ [DCIS] and invasive cancer) of the diseased breast performed within 56 days prior to registration; mammogram for the unaffected contralateral breast is required within 12 months prior to registration
History of invasive breast cancer or contralateral DCIS
Post neoadjuvant chemotherapy, patients must be found to have residual invasive cancer in the breast at the time of definitive surgery; residual cancer is defined as a contiguous focus of residual invasive cancer, in the breast, measuring >= 1 cm in diameter, and with more than minimal cellularity, as per local pathologist determination; please note that in patients that have multifocal or multicentric residual tumors these lesions cannot be added up; the biggest lesion has to measure >= 1 cm in diameter; this is required due to constraints in deoxyribonucleic acid (DNA) extraction for PAM50 analysis* NOTE: The presence of ductal carcinoma in situ (DCIS) without invasion does not qualify as residual invasive disease in the breast* NOTE: Despite lymph node involvement if residual invasive cancer in the breast is < 1 cm in diameter patients are not eligible for participation
Synchronous or previous contralateral invasive breast cancer; (patients with synchronous and/or previous contralateral DCIS or LCIS are eligible)
Any previous history of ipsilateral invasive breast cancer or ipsilateral DCIS; (patients with synchronous or previous ipsilateral LCIS are eligible)
Patients with a history of prior (ipsilateral [ipsi]- and/or contralateral) invasive BC
No history of invasive breast cancer in 5 years prior to study registration other than the current diagnosis (prior ductal breast carcinoma in situ [DCIS] at any time is acceptable)
Patient must have no known breast cancer (DCIS or invasive cancer), not currently undergoing treatment for breast cancer, or planning surgery for a high risk lesion (atypical ductal breast hyperplasia [ADH], atypical lobular breast hyperplasia [ALH], lobular breast carcinoma in situ [LCIS], papilloma, radial scar)
Invasive cancer in the contralateral breast
Patients with previous contralateral invasive breast cancer treated with anti-cancer therapy are eligible
Patients with synchronous ipsilateral invasive breast cancer or any prior history of ipsilateral invasive breast cancer; (patients with previous ipsilateral/contralateral DCIS or previous contralateral invasive breast cancer treated with anti-cancer therapy are eligible)
Patients must not have previous personal history of breast cancer including ductal carcinoma in situ