The use of the MammoSite balloon applicator in re-irradiation of the breast.

PURPOSE: To examine the feasibility of using the MammoSite brachytherapy applicator in the retreatment of the previously irradiated breast.

METHODS AND MATERIALS: Between March 2004 and March 2007, three patients previously treated with external beam radiotherapy were retreated using the MammoSite brachytherapy device. Two patients were treated for an ipsilateral breast tumor recurrence after breast conservation surgery and postoperative irradiation, whereas the third patient developed an in-field breast cancer likely associated with Hodgkin's disease mantle irradiation 27 years before. The recurrent histology of two was ductal carcinoma in situ ([DCIS] one originally presenting as infiltrating ductal carcinoma [IDC] and the other as DCIS), whereas the Hodgkin's disease patient presented with IDC. All patients received a twice-daily tumor dose of 3400 cGy at 340 cGy/fraction. The mean maximum skin dose was 53.4% (range, 49.5-60.3%) of the prescribed dose.

RESULTS: With a mean followup of 32 months, no patient developed a local recurrence. Cosmesis in all three cases as graded by the National Surgical Adjuvant Breast and Bowel Project, cosmesis criteria was excellent (Grade I) in all cases. Dosimetric calculations demonstrated that the device allows for appropriate local irradiation while sparing the previously irradiated skin of the involved breast as defined by the protocol standard.

CONCLUSIONS: Use of the MammoSite device in the treatment of the previously irradiated breast is feasible and may provide adequate local control as well as acceptable cosmesis in carefully selected patients.