Initial outcomes for patients treated on the American Society of Breast Surgeons MammoSite clinical trial for ductal carcinoma-in-situ of the breast.

BACKGROUND: The MammoSite device was designed as a breast brachytherapy applicator and is currently used to deliver accelerated partial breast irradiation (APBI). We hypothesized that APBI delivered with the MammoSite device would be well tolerated and be associated with a good cosmetic outcome in patients with ductal carcinoma-in-situ (DCIS). METHODS: From 2002 to 2004, 191 patients with DCIS were enrolled in a registry trial to assess the MammoSite applicator. Fifteen patients were excluded from analysis because of device- or patient-related factors; 7 patients were excluded after receiving a radiotherapy boost, thus leaving 169 patients available for study. Follow-up information was available for 158 patients. The average length of follow-up was 7.35 months. Forty-three patients had at least 1 year of follow-up. RESULTS: Skin spacing for the MammoSite applicator was as follows: \u3c 5 mm, 3 patients (1.78%); 5 to 7 mm, 18 patients (10.65%); and \u3e or = 7 mm, 148 patients (87.57%). Patients with a device-to-skin distance of \u3e or = 7 mm had the best cosmetic result. Patients with a device-to-skin distance of \u3e or = 7 mm also had a lower incidence of radiation dermatitis. Data on 43 patients who were followed up for at least 1 year confirmed these findings. Additional adverse events were primarily related to skin changes, with breast infections occurring in five patients (3.16%). No patient in the study has experienced a recurrence. CONCLUSIONS: APBI delivered via MammoSite is well tolerated in patients with DCIS, and the lowest toxicity was obtained in patients with the greatest device-to-skin distance. Long-term follow-up data regarding patient satisfaction, cosmesis, and efficacy are needed and will be determined from a recently opened large randomized study