- Patients must not have had external beam radiotherapy for this breast cancer prior to registration. Brachytherapy (interstitial radiation therapy) at the time of breast sparing procedure is acceptable and would not render the patient Ineligible. (If external beam radiotherapy is planned to be given with brachytherapy, it must be delayed until after chemotherapy is complete.) Patients whose most extensive breast surgery was a breast sparing procedure must be planning to receive radiotherapy after chemotherapy is complete.