- Patients must have undergone a segmental mastectomy SM with a level I and ll axillary dissection or sentinel lymph node biopsy Surgical margins at time of local surgery must be negative greater or equal to 2mm for both invasive carcinoma and for non-invasive ductal carcinoma Patients who have post-operative margins which are negative but less than 2mm will be considered eligible if the surgeon states that the margin in question cannot be improved. Patients treated with a mastectomy are NOT eligible