Evaluation of breathing-adapted radiation therapy for right-sided early stage breast cancer patients

Background: Adverse effects of breast irradiation have been an important concern given the increased survival of early stage breast cancer (ESBC) patients with more effective treatments. However, there is paucity of data on the utility of Active Breathing Control (ABC) technique for right-sided ESBC patients. In this study, we assessed the incorporation of ABC into adjuvant Radiation Therapy (RT) of right-sided ESBC patients and report our dosimetric results. Methods: Thirty-six patients receiving whole breast irradiation followed by a sequential tumor bed boost were included in the study. All patients received field-in-field intensity modulated radiation therapy with incorporation of active breathing control-moderate deep inspiration breath-hold (ABC-mDIBH) after breast conserving surgery. Dose-volume parameters in both plans with and without ABC-mDIBH were compared using Mann-Whitney U test. Results: Mean lung dose decreased from 7 Gy to 5.2 Gy (26% reduction) for the total lung (p < 0.001) and from 12.6 to 9.4 Gy (25% reduction) for the ipsilateral lung (p < 0.001). Mean dose decreased from 4.6 Gy to 1.7 Gy (58% reduction) for liver (p < 0.001) and 1.7 Gy to 1.4 Gy (16% reduction) for the heart (p < 0.001). Conclusion: Our study revealed that incorporation of ABC-mDIBH into adjuvant RT of right-sided ESBC patients results in significantly improved critical organ sparing.