Breast conserving therapy with accelerated partial breast versus external beam whole breast irradiation: comparison of imaging sequela and complications in a matched population.

Our purpose was to evaluate and compare the imaging sequela and complications of accelerated partial breast irradiation (APBI) with those occurring in patients treated with standard external beam therapy. Patient selection included those who met the criteria for possible ABPI: age 45 or older; cancer stage T1N0M0 or ductal carcinoma in situ 3 cm or less, and negative surgical margins. One hundred and ninety seven had complete records and films available for review. Ninety-seven (49%) were treated with APBI (MammoSite) and 100(51%) were treated with external beam. Image findings for APBI versus external beam were: distortion 90(93%) versus 83(83%), seroma 67(69%) versus 7(7%), skin edema 52(54%) versus 47(47%), increased stroma 75(77%) versus 66(66%), calcifications 10(10%) versus 6(6%), and fat necrosis 12(12%) versus 6(6%). For APBI, skin and stromal edema was more commonly focal. At imaging, the seroma rate was statistically and significantly different between the two treatment modes (p < 0.0001). For patients treated with APBI, seroma formation was not related to balloon size and only weakly related to lumpectomy cavity size. The complication rate was significantly higher for those treated with APBI (36 versus 20%) and the types and treatment of complications differed. There were three recurrences among the APBI group and none among those treated with external beam radiation.