Key findings
-  When partial breast irradiation (PBI) or accelerated partial breast irradiation (APBI) was compared with whole breast radiation therapy (WBRT) the rates of overall survival were similar.
-  There was no difference on the effects of PBI/APBI on survival, or subsequent mastectomy rate when PBI/APBI was compared with WBRT.
Breast conserving therapy for women with breast cancer consists of local excision of the tumour (achieving clear margins) followed by radiation therapy (RT). RT is given to sterilize tumour cells that may remain after surgery to decrease the risk of local tumour recurrence. Most true recurrences occur in the same quadrant as the original tumour. Whole breast RT may not protect against the development of a new primary cancer developing in other quadrants of the breast.