RAPID: Randomized Trial of Accelerated Partial Breast Irradiation

To determine if Accelerated Partial Breast Irradiation, using 3D CRT, is as effective as Whole Breast Irradiation following breast conserving surgery in women with an new histological diagnosis of ductal carcinoma in situ only or invasive breast cancer without evidence of metastatic disease. Effectiveness will be determined by the rate of ipsilateral breast tumour recurrence. General objective is to improve the convenience and quality of life of female patients who receive breast irradiation.