Dose Sparing Potential of Deep Inspiration Breath-hold Technique for Left Breast Cancer Radiotherapy Organs-at-risk.

BACKGROUND/AIM: To assess if deep inspiration breath-hold (DIBH) technique achieved dose sparing for organs-at-risk in left breast radiotherapy patients in order to reduce long-term complications.

PATIENTS AND METHODS: DIBH and Free-breathing (FB) as a control, CT planning scans obtained for 28 left breast/chest wall (+/- supraclavicular field) patients treated January 2008-December 2013 were retrospectively re-contoured and re-planned. Organs-at-risk examined: lungs, left lung, heart and left anterior descending coronary artery (LADCA). Quantitative statistical analysis of plan dose differences was performed.

RESULTS: Lung dose was not affected by DIBH. Heart Dmax reduced by 34.5% (FB=41.81Gy, SD=3.963Gy vs. DIBH=27.39Gy, SD=12.393Gy, p<0.000004). Heart Dmean reduced by 32.6% (FB=1.817Gy, SD=0.627Gy vs. DIBH=1.224Gy, SD=0.344Gy, p=0.00000083067. LADCA Dmax reduced by 47.8% (DIBH mean=15.56Gy, SD=10.62Gy vs. FB mean=29.82Gy, SD=10.05Gy, p=0.000031, and LADCA Dmean by 52% (DIBH mean=5.23Gy, SD=1.94Gy vs. FB mean=10.88Gy, SD=3.95Gy p=0.000000036027. Amplitude depths were not correlated with dose reductions.

CONCLUSION: DIBH significantly reduces heart and LADCA dose. Further research is required to evaluate potential long-term implications for patients treated DIBH.