Long-term Cosmesis and Toxicity Profile Following Accelerated Partial Breast Irradiation (APBI): Final Analysis of the American Society of Breast Surgeons Breast Brachytherapy Registry Trial

Recent retrospective, claims-based analyses have suggested a potential increased rate of toxicities associated with brachytherapy based APBI. In light of the limitations of such studies, the purpose of this analysis was to examine cosmesis and toxicity profiles as part of the final analysis of the American Society of Breast Surgeons breast brachytherapy registry trial. One thousand four hundred forty-nine cases of early stage breast cancer underwent breast conserving therapy. The single lumen device was used to deliver adjuvant accelerated partial breast irradiation (APBI) (34 Gy in 3.4 Gy fractions). Investigators were asked to evaluate cosmesis at each follow-up visit using the Harvard criteria and also asked to report the presence or absence of any seromas and fat necrosis at any time points after treatment. Follow-up for the final analysis was complete through December 2012. For the entire cohort, the median follow-up was 63.1 months with 974 patients (67.2%), 789 patients (54.5%), and 650 patients (44.9%) having follow-up greater than four, five, and six years, respectively. This represents the final analysis; as per protocol, the study was designed to follow patients for 7 years. The rate of excellent/good cosmesis was 90.6% at 84 months with similar findings noted for the first 400 patients enrolled. The rate of a complication (symptomatic seroma, infection, fat necrosis, and telangiectasias) at one year/any time point was 24.2%/38.5% while the rate of non-infectious complications at one year/any time point was 14.8%/28.9%. The incidence rate of any seroma, symptomatic seroma, and seroma requiring drainage are 28.9%, 13.4%, and 12.2% at any time point and 3.1%, 0.6%, and 0.5% beyond 24 months. The rate of infection at any time was 9.6%; the rate was 11.8% for open cavity and 7.8% for closed cavity with a 0.1% incidence beyond 24 months. The incidence of telangiectasias was 2.6% within the first 12 months, 2.3% at 12-18 months, 3.2% at 18-24 months, and 6.8% beyond 24 months. The final toxicity analysis from the American Society of Breast Surgeons Registry confirms the previously noted excellent cosmesis and toxicity and fails to confirm limited, retrospective analyses that had suggested higher rates of toxicity for APBI. The incidence of toxicities beyond 24 months from treatment remains low with respect to telangiectasias, fat necrosis, and seromas.