Predictors of cosmetic outcome following MammoSite breast brachytherapy: a single-institution experience of 100 patients with two years of follow-up.

Abstract

To identify the factors that predict for excellent cosmesis in patients who receive MammoSite breast brachytherapy (MBT). One hundred patients with Stage 0, I, or II 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 (192)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). 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. The acute and late-term toxicity profiles of MBT have been acceptable. Cosmetic outcome is improved by proper patient selection and infection prevention.