Development and evaluation of whole breast irradiation with volumetric modulated arc therapy-based hybrid intensity-modulated radiotherapy after breast conserving surgery for breast cancer / 中华放射肿瘤学杂志

ABSTRACT

Objective To develop whole breast irradiation with volumetric-modulated arc therapy (VMAT)-based hybrid intensity-modulated radiotherapy (IMRT) after breast conserving surgery for breast cancer,and to evaluate its value in clinical application.Methods Ten patients with breast cancer undergoing breast conserving surgery were enrolled.Two radiotherapy plans were designed based on hybrid fixed-beam IMRT/IMRT technique and hybrid VMAT/IMRT technique,respectively.One group received whole breast irradiation with a prescribed dose of 50 Gy in 25 fractions.The other group received whole breast irradiation with a prescribed dose of 50 Gy in 25 fractions,as well as simultaneous integrated boost to the tumor bed with 60 Gy in 25 fractions.The dosimetric parameters and delivery efficiency were compared between the two plans using paired t test.Results For patients treated with whole breast irradiation alone,there were no significant differences in conformity index and homogeneity index of target volume between the two plans (P=0.866,0.056);however,compared with the hybrid fixed-beam IMRT/IMRT technique,the hybrid VMAT/IMRT technique significantly increased the doses to organs at risk (OARs) and the number of monitor units (MUs) in the intensity-modulated field (P=0.000-0.050,P=0.002).For patients treated with whole breast irradiation with a simultaneous integrated boost to the tumor bed;however,the hybrid VMAT/IMRT technique significantly reduced the doses to the lung and spinal cord,number of MUs in intensity-modulated field,and delivery time compared with the hybrid fixed-beam IMRT/IMRT technique (P=0.004,0.001,0.000,0.000).Conclusions For patients treated with whole breast irradiation with a simultaneous integrated boost to the tumor bed,the hybrid VMAT/IMRT technique is highly promising for clinical application due to better OAR sparing and higher delivery efficiency.