Once Daily Accelerated Partial Breast Irradiation: Preliminary Results with Helical Tomotherapy®.

Background: Accelerated partial breast irradiation (APBI) is becoming an option for patients with low-risk breast cancer. The current practice is 38.5 Gy in 10 fractions b.i.d. over 5 days. This fractionation has a higher bioequivalent dose compared to the standard schedule. We report on preliminary results of once-daily APBI in patients treated with TomoTherapy (R). Patients and Methods: Patients with unifocal-breast disease who underwent breastconserving surgery were enrolled in the study. Treatment was administered with TomoTherapy, by contouring in accordance with the NSABP B-39/RTOG 0413 APBI protocol. Treatment schedule was 38.5 Gy in 10 once-daily fractions. EORTC Cosmetic Rating System was adopted for cosmetic outcome. Results: From 2010 to 2013, 111 patients were treated. With a median follow-up of 34 months, no ipsilateral breast recurrence was observed. Very few patients (1-4%) assessed their cosmetic outcome as fair or poor during follow-up. Conclusion: Once-daily APBI with TomoTherapy yielded good cosmetic results without compromising local control efficacy.