Why is partial-breast irradiation still investigational.

The investigational nature of partial breast irradiation (PBI) remains an area of controversy in the field of breast radiotherapy. While we have a long track record of conducting and strongly supporting the research in this area, we have chosen the more cautious approach of continuing to offer PBI only as part of a trial, open to selected breast cancer patients at low risk of local recurrence. This position reflects the fact that existing whole breast radiotherapy has revealed very successful in controlling local recurrences and it remains the safest choice for the patient. Our thinking has been reinforced by the recent data linking the prevention of recurrence to long term breast cancer survival: until more is known about PBI safety, its indiscriminate use may deprive some women from their best chance of fighting breast cancer. Considerations regarding the correct interpretation of the available evidence in view of the still limited duration of follow up and of the pattern of local recurrence of breast cancer sustain our position that PBI can be offered only in the context of a clinical trial. Unfortunately, more time and data are warranted for PBI to be legitimately recognized a standard radiotherapy approach in breast conservation therapy.