Radiation Therapy With or Without Trastuzumab in Treating Women With Ductal Carcinoma In Situ Who Have Undergone Lumpectomy

Inclusion Criteria: * The patient must have consented to participate and must have signed and dated an appropriate Institutional Review Board (IRB)-approved consent form that conforms to federal and institutional guidelines for the study treatment and for the pre-entry tumor block submission for HER2 testing and B-43 correlative studies * Patients must have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 (0 = fully active, able to carry on all pre-disease performance without restriction; 1 = restricted in physically strenuous activity but ambulatory) * On histologic examination, the tumor must be ductal carcinoma in situ (DCIS) (patients with mixed DCIS and lobular carcinoma in situ \[LCIS\] are eligible) * The DCIS must be HER2-positive as determined by central testing * Estrogen and/or progesterone receptor status must be determined prior to randomization (patients with DCIS that is hormone receptor positive or negative are eligible) * All DCIS must have been resected by lumpectomy * The margins of the resected specimen must be histologically free of DCIS; for patients in whom pathologic examination demonstrates DCIS present at the line of resection, re-excision(s) may be performed to obtain clear margins (patients who require mastectomy are not eligible) * If axillary staging is performed, nodal staging must be pN0, pN0(i-), pN0(i+) which is defined as isolated tumor cells =\< 0.2 mm, regardless of the method of detection, i.e., immunohistochemis…