左侧乳腺癌局部区域放疗联合深吸气屏气：与切线野调强放疗相比，容积调强弧形放疗是否能进一步降低心脏剂量？

Left-sided breast cancer loco-regional radiotherapy with deep inspiration breath-hold: Does volumetric-modulated arc radiotherapy reduce heart dose further compared with tangential intensity-modulated radiotherapy?

作者信息

Pham Trang T, Ward Rachel, Latty Drew, Owen Catherine, Gebski Val, Chojnowski Jacek, Kelly Christopher, Ahern Verity, Tiver Kenneth, Stuart Kirsty, Wang Wei

机构信息

Department of Radiation Oncology, Crown Princess Mary Cancer Centre Westmead, Sydney, New South Wales, Australia.

Breast Cancer Institute, Westmead, Sydney, New South Wales, Australia.

出版信息

J Med Imaging Radiat Oncol. 2016 Aug;60(4):545-53. doi: 10.1111/1754-9485.12459. Epub 2016 Apr 20.

DOI:10.1111/1754-9485.12459

PMID:27094588

Abstract

INTRODUCTION

Left-sided breast cancer radiotherapy has been associated with an increase in cardiac mortality. This study investigated the potential heart-sparing effect of volumetric-modulated arc radiotherapy (VMAT). We compared VMAT to tangential intensity-modulated radiotherapy (t-IMRT) in the loco-regional treatment of left-sided breast cancer, including internal mammary nodal irradiation, based on deep inspiration breath-hold (DIBH) and free-breathing (FB).

METHODS

Radiotherapy for 15 patients was re-planned. Four plans were compared: t-IMRT-DIBH; VMAT-DIBH; t-IMRT-FB; VMAT-FB. Prescribed dose was 50 Gy in 25 fractions. T-IMRT plans were generated using tangentially orientated fields. VMAT plans were generated using two partial arcs (average arc 190°).

RESULTS

Mean heart dose (MHD) was 5 ± 2.4 Gy, 5.7 ± 1.4 Gy, 9.7 ± 3.3 Gy and 8.1 ± 2.0 Gy for t-IMRT-DIBH, VMAT-DIBH, IMRT-FB and VMAT-FB respectively. The difference in MHD between IMRT-DIBH and VMAT-DIBH was not significant (P = 0.14). VMAT-DIBH significantly spared the volume of heart irradiated to doses of 20 Gy and above (p < 0.05), however, resulted in a significantly higher V5 Gy (P < 0.001), compared to t-IMRT-DIBH. VMAT-DIBH resulted in higher combined lung mean (11 ± 0.8 Gy vs. 8.8 ± 1.1 Gy, P < 0.001) and higher contralateral breast mean dose (5 ± 1 Gy vs. 1.6 ± 1.2 Gy, P < 0.001) compared with t-IMRT-DIBH.

CONCLUSIONS

On average, there was no significant difference in MHD between VMAT-DIBH and t-IMRT-DIBH. However, VMAT-DIBH was found to benefit a select group of patients. For patients in whom the MHD was >6.3 Gy with t-IMRT-DIBH, the use of VMAT-DIBH resulted in a benefit in reducing the MHD.

摘要

引言

左侧乳腺癌放疗与心脏死亡率增加相关。本研究调查了容积调强弧形放疗（VMAT）潜在的心脏保护作用。我们在基于深吸气屏气（DIBH）和自由呼吸（FB）的左侧乳腺癌局部区域治疗（包括内乳淋巴结照射）中，将VMAT与切线野调强放疗（t-IMRT）进行了比较。

方法

对15例患者的放疗计划进行重新规划。比较了四个计划：t-IMRT-DIBH；VMAT-DIBH；t-IMRT-FB；VMAT-FB。处方剂量为50 Gy，分25次给予。t-IMRT计划使用切线方向的射野生成。VMAT计划使用两个部分弧形（平均弧190°）生成。

结果

t-IMRT-DIBH、VMAT-DIBH、IMRT-FB和VMAT-FB的平均心脏剂量（MHD）分别为5±2.4 Gy、5.7±1.4 Gy、9.7±3.3 Gy和8.1±2.0 Gy。IMRT-DIBH和VMAT-DIBH之间的MHD差异不显著（P = 0.14）。VMAT-DIBH显著减少了心脏受照剂量在20 Gy及以上的体积（p < 0.05），然而，与t-IMRT-DIBH相比，其V5 Gy显著更高（P < 0.001）。与t-IMRT-DIBH相比，VMAT-DIBH导致肺平均剂量更高（11±0.8 Gy对8.8±1.1 Gy，P < 0.001），对侧乳腺平均剂量更高（5±1 Gy对1.6±1.2 Gy，P < 0.001）。