Accelerated partial breast irradiation using the MammoSite device: early technical experience and short-term clinical...

The MammoSite brachytherapy system is a novel form of intracavitary accelerated partial breast irradiation (APBI) that allows treatment over a 5- to 7-day course after breast conserving surgery (BCS). Fifty-one patients with invasive breast carcinoma underwent BCS and APBI using the MammoSite device, with 30 (59%) patients having drain placement in the lumpectomy cavity. Main outcome measures included time to initiating APBI, cosmesis using the Harvard Scale, and local and distant tumor recurrence with short-term follow-up. Five (9.8%) devices were explanted because of unfavorable final pathological findings or infection. Mean time to the start of APBI in patients without drain placement was 7.2 days (range, 5-12 days) compared with 5.1 days (range, 3-8 days) in patients with drains (P = 0.003). Cosmetic results were excellent in 25 (54.3%) patients, good in 19 (41.3%) patients, and fair in 2 (4.4%) patients. With a mean follow-up of 16 months (range, 6-38 months), no ipsilateral breast recurrences developed in any of the 51 patients. Thirteen patients had at least a 2-year follow-up. Two patients developed brain metastases and died at 19 and 23 months, respectively. The favorable short-term outcomes support further studies comparing APBI with standard whole-breast irradiation in patients undergoing BCS.