Partial breast irradiation. Patient selection, guidelines for treatment, and current results.

Studies evaluating selected patients treated with partial breast irradiation (PBI) in accelerated fractionation schemes have demonstrated the equivalence of PBI with traditional whole-breast irradiation. The major advantage of PBI is the time compression of treatment down to less than 1 week compared with 6.5 weeks for whole-breast external beam treatments. Four techniques are available to deliver PBI. These include interstitial brachytherapy multicatheter systems, the Mammosite Radiation Therapy System applicator, external beam three-dimensional conformal radiation therapy and intraoperative radiation therapy. For the two brachytherapy techniques of multicatheter implantation and the Mammosite, accurate placement is achieved with image guidance via intraoperative ultrasonography, mammography, and/or CT scanning. Technologies such as image-guided cone beam CT assure accurate delivery of PBI with external beam three-dimensional conformal radiation therapy. Results of PBI show excellent control rates with mild toxicities; cosmetic outcomes are good to excellent in the vast majority of patients.