Abstract
Background
This study aimed to compare dosimetry of the target region and organ at risk (OAR) according to two different radiation plans for patients after breast-conserving surgery (BCS), hypofractionated whole breast irradiation (HFWBI) combined with an additional sequential boost (SEQ) versus simultaneous integrated boost (SIB), and further explore better radiotherapy after breast-conserving surgery.
Methods
We included 56 patients with early-stage left-sided breast cancer. Hybrid volumetric modulated arc therapy (H-VMAT) plus sentinel lymph node biopsy was given to all participants. The following SIB and SEQ treatments were planned for each patient. The radiation doses delivered to OAR and dose-volume histogram were analyzed. The comparison of the max dose (Dmax), the mean dose (Dmean), the min dose (Dmin), and the volume of each organ that received x Gy (Vx) was accomplished.
Results
The V5, V10, and V20 of the heart and the ipsilateral lung were lower in the SIB plan than SEQ, while among patients receiving the SIB plan, the V5 and V10 of the right and the left ventricle were lower. The Dmean for the heart, left anterior descending (LAD), right ventricle, left ventricle and the ipsilateral lung was lower for the SIB plan (heart: 5.24 ± 0.75 Gy vs. 6.92 ± 0.92Gy, p < 0.001; lad: 9.27 ± 1.07Gy vs. 11.86 ± 1.40Gy, p < 0.001; right ventricle 6.39 ± 1.54Gy vs. 8.39 ± 1.88Gy, left ventricle 6.10 ± 1.33Gy vs. 8.54 ± 1.80Gy, p < 0.001; lung: 9.28 ± 1.07Gy vs. 11.86 ± 1.41Gy, p < 0.001).
Conclusions
Regarding the dosimetry among the heart, LAD, ventricle, and left lung, SIB radiotherapy achieved better results, suggesting that the SIB plan might be more suitable for postoperative radiotherapy after BCS for early-stage breast cancer patients. We also witnessed that large daily radiation doses could be safe and effective when combined with the radiobiology of breast cancer.