Stick Line B, Yu Jen, Maraldo Maja V, Aznar Marianne C, Pedersen Anders N, Bentzen Søren M, Vogelius Ivan R
Department of Clinical Oncology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark; Niels Bohr Institute, Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
Maryland Proton Treatment Center, University of Maryland School of Medicine, Baltimore, Maryland.
Int J Radiat Oncol Biol Phys. 2017 Mar 15;97(4):754-761. doi: 10.1016/j.ijrobp.2016.12.008. Epub 2016 Dec 13.
The study aims to perform joint estimation of the risk of recurrence caused by inadequate radiation dose coverage of lymph node targets and the risk of cardiac toxicity caused by radiation exposure to the heart. Delivered photon plans are compared with realistic proton plans, thereby providing evidence-based estimates of the heterogeneity of treatment effects in consecutive cases for the 2 radiation treatment modalities.
Forty-one patients referred for postlumpectomy comprehensive nodal photon irradiation for left-sided breast cancer were included. Comparative proton plans were optimized by a spot scanning technique with single-field optimization from 2 en face beams. Cardiotoxicity risk was estimated with the model of Darby et al, and risk of recurrence following a compromise of lymph node coverage was estimated by a linear dose-response model fitted to the recurrence data from the recently published EORTC (European Organisation for Research and Treatment of Cancer) 22922/10925 and NCIC-CTG (National Cancer Institute of Canada Clinical Trials Group) MA.20 randomized controlled trials.
Excess absolute risk of cardiac morbidity was small with photon therapy at an attained age of 80 years, with median values of 1.0% (range, 0.2%-2.9%) and 0.5% (range, 0.03%-1.0%) with and without cardiac risk factors, respectively, but even lower with proton therapy (0.13% [range, 0.02%-0.5%] and 0.06% [range, 0.004%-0.3%], respectively). The median estimated excess absolute risk of breast cancer recurrence after 10 years was 0.10% (range, 0.0%-0.9%) with photons and 0.02% (range, 0.0%-0.07%) with protons. The association between age of the patient and benefit from proton therapy was weak, almost non-existing (Spearman rank correlations of -0.15 and -0.30 with and without cardiac risk factors, respectively).
Modern photon therapy yields limited risk of cardiac toxicity in most patients, but proton therapy can reduce the predicted risk of cardiac toxicity by up to 2.9% and the risk of breast cancer recurrence by 0.9% in individual patients. Predicted benefit correlates weakly with age. Combined assessment of the risk from cardiac exposure and inadequate target coverage is desirable for rational consideration of competing photon and proton therapy plans.
本研究旨在联合评估因淋巴结靶区辐射剂量覆盖不足导致的复发风险以及因心脏受到辐射暴露导致的心脏毒性风险。将已实施的光子治疗计划与实际的质子治疗计划进行比较，从而为这两种放射治疗方式在连续病例中的治疗效果异质性提供基于证据的评估。
纳入41例因左侧乳腺癌接受保乳术后全淋巴结光子照射的患者。通过点扫描技术从2个正前方射束进行单野优化，对质子治疗对照计划进行优化。采用Darby等人的模型评估心脏毒性风险，通过拟合最近发表的欧洲癌症研究与治疗组织（EORTC）22922/10925和加拿大国家癌症研究所临床试验组（NCIC-CTG）MA.20随机对照试验的复发数据的线性剂量反应模型，评估淋巴结覆盖不足后的复发风险。
在80岁时接受光子治疗，心脏发病的额外绝对风险较小，有和没有心脏危险因素时的中位数分别为1.0%（范围0.2%-2.9%）和0.5%（范围0.03%-1.0%），但质子治疗时更低（分别为0.13%[范围0.02%-0.5%]和0.
