Long-term outcome of accelerated partial breast irradiation using a multilumen balloon applicator in a patient with existing breast implants

Purpose: Accelerated partial breast irradiation is now an accepted component of breast-conserving therapy. However, data regarding long-term outcomes of patients treated with multilumen catheter systems who have existing breast implants are limited. Methods and Materials: We report the treatment and outcome of our patient who had existing bilateral silicone subpectoral implants at the time of presentation. Ultrasound-guided core needle biopsy of the right breast showed infiltrating mucinous carcinoma. Right breast lumpectomy revealed an 8mm area of infiltrating ductal carcinoma with mucinous features and nuclear grade 1. A 4-5cm Contura (Bard Biopsy Systems, Tempe, AZ) device was placed, and she was treated over the course of 5days twice daily to a dose of 34Gy using a high-dose-rate iridium-192 source. Results: The planning target volume for evaluation was 73.9 cc. The percentage of the planning target volume for evaluation receiving 90%, 95%, and 100% of the prescribed dose was 99.9%, 99.3%, and 97.8%, respectively. The total implant volume was 234.5 cc and received a mean dose of 15.4Gy and a maximum dose of 72.8Gy. The percentage of implant volume receiving 50%, 75%, 100%, and 200% of the prescribed dose was 31.1%, 16.5%, 8.6%, 2.0%, and 0%, respectively. Maximum skin dose was 97% of the prescribed dose. With a followup of nearly 5years, she continues to be cancer free with minimal late toxicities and good to excellent cosmetic outcome. Conclusions: Accelerated partial breast irradiation using a multilumen balloon applicator in patients with existing breast implants can safely be performed with excellent long-term cosmetic outcome. Further studies are needed to establish the absolute dosimetric tolerance of breast implants.