Observational Study for Ductal Breast Carcinoma In Situ

Inclusion criteria 1. Patient must have histologically confirmed ductal carcinoma in situ (DCIS) in a single breast (presence of lobular carcinoma in situ (LCIS) or other benign breast disease in addition to DCIS is acceptable). 2. Patient must have the DCISionRT test ordered during routine patient care. 3. Patient must be eligible for or have recently completed breast conserving surgery. 4. Patient must be eligible to receive radiation and/or systemic treatment. 5. Patient must be 30 to 85 years old. 6. Patient must have tumor size of less than 6 cm. 7. Patient must have been diagnosed with DCIS within 120 days of consent. Exclusion criteria 1. Patient tissue is insufficient to generate DCISionRT test results or required DCISionRT inputs (age, tumor size, margin status, palpability) are missing. 2. Patient has evidence of invasive breast cancer, including microinvasion, lymph node involvement, or Paget's disease of the nipple or suspicious mammogram findings in the lymph nodes or contralateral breast. 3. Patient has been surgically treated with an ipsilateral mastectomy for primary DCIS. 4. Patient has had any prior ipsilateral or contralateral breast DCIS or invasive breast cancer. 5. Patient has a prior history of in-field radiation in the ipsilateral breast. 6. Patient has had prior systemic endocrine or chemotherapy prior to testing. 7. Patient is pregnant.