The feasibility study of a hybrid coplanar arc technique versus hybrid intensity-modulated radiotherapy in treatment of early-stage left-sided breast cancer with simultaneous-integrated boost

Abstract

This study demonstrated the feasibility and advantages of a hybrid, volumetric arc therapy technique that used two 90° coplanar arcs and two three-dimensional conformal tangential beams in the simultaneous-integrated boost radiotherapy of left-sided breast cancer after breast-conserving surgery. A total of nine patients with stage I, left-sided breast cancer who underwent breast-conserving surgery were selected for this retrospective study. For each patient, a hybrid arc plan was generated and then compared with two hybrid intensity-modulated radiotherapy plans. All plans were optimized using the same objectives and dose constraints. The prescription dose was 50.4 Gy to the planning target volume with simultaneous boost to 60 Gy to the expanded gross target volume in 28 fractions. The differences among these hybrid plans were analyzed by the Kolmogorov–Smirnov test or the Wilcoxon rank sum test. The hybrid arc plans achieved the clinical requirements of target dose coverage and normal tissue (NT) dose constraints. It was found that the hybrid arc plans showed advantages in the conformity index of the expanded gross target volume, the V5 of the heart, the D2 of the left ventricle, and the D2 and V50.4 of NTs. The average beam-on time and monitor units of the hybrid arc plans were significantly lower (P < 0.001).

Hybrid volumetric modulated arc therapy for hypofractionated radiotherapy of breast cancer: a treatment planning study

“…The researchers recommend H-VMAT for hypofractionated breast RT in DIBH due to reduced MU and treatment delivery time. Another study by Chen et al [27] consistently reported advantages of H-VMAT over H-IMRT with regard to dose conformity, heart dose, and delivery time. They compared H-VMAT with two different H-IMRT designs in the treatment of early-stage leftsided breast cancer.…”

“…The basis for proper dose application with H-VMAT to the patient is the existence of good reproducibility of the patient positioning. Dynamic techniques like H-VMAT may be prone to intra-and interfractional positioning uncertainties, which demand reproducibility of patient positioning both in treatment planning and execution [27,[29][30][31]. In order to minimize positioning uncertainties and deviations between planned and delivered dose distributions, CT acquisition and radiotherapy should be carried out in DIBH.…”

Response to the comments on “The feasibility study of a hybrid coplanar arc technique versus hybrid intensity-modulated radiotherapy in treatment of early-stage left-sided breast cancer with simultaneous-integrated boost. J Med Phys 2017;42:1-8”

“…However, these techniques are not thoroughly implemented at each hospital, including the authors' institutions. In our manuscript,[ 1 ] we proposed hybrid plans (three-dimensional conformal radiotherapy [3DCRT] + intensity-modulated radiation therapy [IMRT] or 3DCRT + volumetric modulated arc therapy [VMAT]) solely for simultaneous integrated boost treatment delivery. As indicated in the manuscript, “The rationale of using two coplanar 90° arcs in the hybrid VMAT technology is as follows: (1) In the VMAT plan, two arcs are needed to optimize dose distribution when dealing with a complex target; (2) the target is an arc that was nearly 90° along the chest wall, and the 90° arc in tangential direction enters the target without irradiating much of the lung.” In the left breast irradiation, the target dose inhomogeneity and doses to the organs at risk (OAR), especially the heart, ipsilateral lung, and contralateral breast, are the major limitations of 3DCRT.…”