Predictors of cosmetic outcome following mammosite breast brachytherapy: A single-institution experience of 100 patients with two years of follow-up

Purpose: To identify the factors that predict for excellent cosmesis in patients who receive MammoSite breast brachytherapy (MBT). Methods and Materials: One hundred patients with Stage 0, 1, or 11 adenocarcinoma of the breast underwent adjuvant therapy using MBT. A dose of 34 Gy, delivered in 10 fractions twice daily, was prescribed to 1-cm depth using 112 Ir high-dose-rate brachytherapy. Patients were assessed for acute toxicity on the day of therapy completion, 4 weeks after therapy, and at least every 3 months by radiation, surgical, and/or medical oncologists. All available data were reviewed for documentation of cosmesis and rated using the Harvard Scale. All patients had a minimum follow-up of 6 months (median = 24 months). Results: Of 100 patients treated, 90 had adequate data and follow-up. Cosmesis was excellent in 62 (68.9%), good in 19 (21.1%), fair in 8 (8.9%), and poor in 1 (1.1%) patient. Using stepwise logistic regression, the factors that predicted for excellent cosmesis were as follows: the absence vs. presence of infection (p = 0.017), and the absence vs. presence of acute skin toxicity (p = 0.026). There was a statistically significant association between acute skin toxicity (present vs. absent) and balloon-to-skin distance (< 8 vs. >8 mm,p = 0.001). Factors that did not predict for cosmesis were age, balloon placement technique, balloon volume, catheter days in situ, subcutaneous toxicity, and chemotherapy or hormonal therapy. Conclusions: The acute and late-term toxicity profiles of MBT have been acceptable. Cosmetic outcome is improved by proper patient selection and infection prevention. (C) 2007 Elsevier Inc.