Accelerated Partial Breast Irradiation Using the MammoSite Device: Early Technical Experience and Short-Term Clinical Follow-Up

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.