Treatment Results of MammoSite Catheter in Combination with Whole-breast Irradiation.

To report the initial outcomes of patients treated with the MammoSite brachytherapy device (MSBT) as a boost followed by external whole-breast irradiation (WBI).From June 2011 to March 2014, 107 patients (typically with pT1-2, pN0-1, M0 disease) were treated with breast-conserving therapy and adjuvant radiotherapy with MSBT (15 Gy in 2.5-Gy fractions) followed by WBI (median=50.4 Gy). Toxicity was classified according to the Common Terminology Criteria for Adverse Events v3.0. The median follow-up was 21 months.To date, no ipsilateral breast-tumor recurrences have been observed; 102 patients (95%) were alive at last follow-up. Two patients (2%) developed distant metastases. Five patients (5%) died during follow-up, only one as a result of breast cancer. The 2-year disease-free survival was 95±3%. The incidence of asymptomatic and symptomatic seroma in 90 days after MSBT was 28% and 10%, respectively. Infectious mastitis was observed in three patients (3%), who were treated successfully with antibiotics. Only three patients (3%) developed RT-induced dermatitis greater than grade 2 after WBI.The boost technique used in this study seems to provide excellent local control with acceptable toxicity, similar to the results observed with other forms of interstitial accelerated partial-breast irradiation as a boost. Long-term follow-up is necessary to refine the patient selection criteria and to assess efficacy and late toxicities.