The standard of care for treating early-stage invasive breast cancer or ductal carcinoma in situ (DCIS) is a combination of lumpectomy and radiotherapy. The traditional method of giving radiation therapy after a lumpectomy is to direct it to the whole breast. With partial breast irradiation (PBI), the radiation is given only to the area of the breast where the cancer was removed.
The purpose of this study is to determine the side effects and effectiveness of delivering PBI instead of whole breast irradiation (WBI) in women with early-stage breast cancer or DCIS. Another purpose of this study is to examine the rate of recurrence of cancer in the same breast as the original cancer in patients who receive PBI.
With WBI, radiation therapy is given five days a week for five to seven weeks. With PBI, radiation therapy is given for a few minutes a day, once a day, five days a week for two weeks.