Intraoperative Radiation Therapy (IORT) in DCIS

Inclusion Criteria: * Pathologically confirmed DCIS of the breast * Clinical ≤ 3.0 cm unifocal lesion * No clinical or pathological evidence of nodal involvement * Operable DCIS, suitable for breast conserving surgery * Plans to administer irradiation to the breast only * Eastern Cooperative Oncology Group (ECOG) performance status of 0-3, however grade 4 patients may be enrolled at the discretion of the treating radiation oncologist * Must have had a diagnostic mammogram or MRI performed within last 6 months * Women of child-bearing potential must have a negative pregnancy test in accordance to institutional guidelines * Women of child-bearing potential must agree to use adequate contraceptive precautions (defined as oral contraceptives, intrauterine devices, surgical contraceptives, or combination of condom and spermicide) from the time of negative pregnancy test through the radiation treatment period. * English or Spanish speaking * Able to sign informed consent * Amenable to regular follow-up (according to research policies) for at least 5 years. Exclusion Criteria: * Histologic or clinical evidence of invasive breast cancer * Multicentric cancer in the ipsilateral breast as diagnosed by clinical examination, imaging, or pathologic assessment, not amenable to excision with negative margins with a single lumpectomy * Synchronous bilateral breast cancer at the time of diagnosis * Pathologic or imaging evidence of lymph node involvement * Any severe concomitant disease that may limit their life expectancy to less than 5 years. * Prior history of breast cancer or in-field radiation in the ipsilateral breast. * Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements. * Pregnant or breast feeding women