Intra-Operative Radiation Registry

Inclusion Criteria: * Female gender * Age ≥ 45 * cT1-2N0, \<3.5cm invasive breast cancer, estrogen-receptor positive or DCIS of breast, Grade 1-2, mammographically detected, \< 2.5 cm, estrogen-receptor positive * Suitable for breast conserving surgery * No contraindication to radiation * Mammogram within 6 months of planned procedure * Fitness for lumpectomy under general anesthesia * Planned to receive IORT Exclusion criteria * Known axillary lymph node positive breast cancer (negative biopsy not required) * Multicentric cancer in the same breast as diagnosed by clinical examination, mammography, ultrasound, MRI or pathologic assessment, not amenable to excision with negative margins with a single lumpectomy. * Patients known to have BRCA 1/2 (breast cancer 1, breast cancer 2) gene * Patients undergoing neoadjuvant chemotherapy * Pregnancy