3. Eligible women include (American Joint Committee on Cancer) AJCC 7th ed. Stage cN0 or cN1 subsequently staged after surgery as Stage pIB (N1mic), pIIA, pIIB, pIIIA, or pIIIB: note that ypN0 will also be eligible if pathologic confirmation of nodal involvement was documented prior to neoadjuvant chemotherapy and the patient was found to be node negative at the time of surgery. Note that women less than 50 years of age, women who received chemotherapy, patients staged as pN0 (i+ or mol+), and large-breasted women are eligible for enrollment.