Experience with an electronic brachytherapy technique for intracavitary accelerated partial breast irradiation

Objectives: Phase IV study evaluated the safety and device performance of an electronic brachytherapy system (Axxent Electronic Brachytherapy System) as adjuvant therapy for early-stage breast cancer. Methods: Patients were ≥50 years of age and had completely resected invasive ductal carcinoma or ductal carcinoma in situ (<2.0 cm), with N0 M0 and negative microscopic margins of ≥1 mm. The balloon applicator was placed in a closed cavity with a balloon surface to skin distance of ≥7 mm. The prescribed dose was 3.4 Gy/fraction prescribed to 1 cm beyond the balloon surface twice daily (BID) for 10 fractions. Results: Of 65 patients consented, 21 (32%) were not eligible for treatment, and 44 (68%) were treated, with 6-months follow-up in 43 and 1-year follow-up in 36. The prescribed radiation treatment was successfully delivered in 42/44 (95.4%) patients; one was unsuccessful due to a controller issue and the other declined the final fraction following a balloon deflation. Side effects were as anticipated and generally manageable. Four CTCAE v3 grade 3 toxicities were reported: blistering (1), breast tenderness (1), and moist desquamation (2); all have resolved. The most common grade 2 toxicity was erythema. There were no device-related serious adverse events. Conclusions: Early experience demonstrates that the electronic brachytherapy system performed as expected. Electronic brachytherapy has similar acute toxicity profiles to other high dose rate approaches for accelerated partial breast irradiation and offers the convenience of having the treatment in an unshielded room.