Binkley Michael S, Shrager Joseph B, Leung Ann N, Popat Rita, Trakul Nicholas, Atwood Todd F, Chaudhuri Aadel, Maxim Peter G, Diehn Maximilian, Loo Billy W
Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California.
Division of Thoracic Surgery, Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California.
Int J Radiat Oncol Biol Phys. 2014 Sep 1;90(1):216-23. doi: 10.1016/j.ijrobp.2014.05.025. Epub 2014 Jul 8.
Lung volume reduction surgery (LVRS) improves dyspnea and other outcomes in selected patients with severe emphysema, but many have excessive surgical risk for LVRS. We analyzed the dose-volume relationship for lobar volume reduction after stereotactic ablative radiation therapy (SABR) of lung tumors, hypothesizing that SABR could achieve therapeutic volume reduction if applied in emphysema.
We retrospectively identified patients treated from 2007 to 2011 who had SABR for 1 lung tumor, pre-SABR pulmonary function testing, and ≥6 months computed tomographic (CT) imaging follow-up. We contoured the treated lobe and untreated adjacent lobe(s) on CT before and after SABR and calculated their volume changes relative to the contoured total (bilateral) lung volume (TLV). We correlated lobar volume reduction with the volume receiving high biologically effective doses (BED, α/β = 3).
27 patients met the inclusion criteria, with a median CT follow-up time of 14 months. There was no grade ≥3 toxicity. The median volume reduction of the treated lobe was 4.4% of TLV (range, -0.4%-10.8%); the median expansion of the untreated adjacent lobe was 2.6% of TLV (range, -3.9%-11.6%). The volume reduction of the treated lobe was positively correlated with the volume receiving BED ≥60 Gy (r(2)=0.45, P=.0001). This persisted in subgroups determined by high versus low pre-SABR forced expiratory volume in 1 second, treated lobe CT emphysema score, number of fractions, follow-up CT time, central versus peripheral location, and upper versus lower lobe location, with no significant differences in effect size between subgroups. Volume expansion of the untreated adjacent lobe(s) was positively correlated with volume reduction of the treated lobe (r(2)=0.47, P<.0001).
We identified a dose-volume response for treated lobe volume reduction and adjacent lobe compensatory expansion after lung tumor SABR, consistent across multiple clinical parameters. These data serve to inform our ongoing prospective trial of stereotactic ablative volume reduction (SAVR) for severe emphysema in poor candidates for LVRS.
肺减容手术（LVRS）可改善部分重度肺气肿患者的呼吸困难及其他预后，但许多患者接受LVRS的手术风险过高。我们分析了肺肿瘤立体定向消融放疗（SABR）后肺叶容积减少的剂量-容积关系，推测SABR应用于肺气肿时可实现治疗性容积减少。
我们回顾性纳入了2007年至2011年期间接受过1次肺肿瘤SABR治疗、SABR前进行过肺功能测试且有≥6个月计算机断层扫描（CT）影像随访的患者。我们在SABR前后的CT图像上勾勒出治疗肺叶和未治疗的相邻肺叶，并计算它们相对于勾勒出的全肺（双侧）容积（TLV）的容积变化。我们将肺叶容积减少与接受高生物等效剂量（BED，α/β = 3）的容积进行相关性分析。
27例患者符合纳入标准，CT中位随访时间为14个月。无≥3级毒性反应。治疗肺叶的中位容积减少为TLV的4.4%（范围：-0.4% - 10.8%）；未治疗的相邻肺叶的中位容积增加为TLV的2.6%（范围：-3.9% - 11.6%）。治疗肺叶的容积减少与接受BED≥60 Gy的容积呈正相关（r(2)=0.45，P = 0.0001）。在根据SABR前1秒用力呼气容积高低、治疗肺叶CT肺气肿评分、分次照射次数、随访CT时间、中央型与周围型位置以及上叶与下叶位置确定的亚组中，这种相关性依然存在，各亚组效应大小无显著差异。未治疗的相邻肺叶的容积增加与治疗肺叶的容积减少呈正相关（r(2)=0.47，P < 0.0001）。
我们确定了肺肿瘤SABR后治疗肺叶容积减少和相邻肺叶代偿性扩张的剂量-容积反应，该反应在多个临床参数中保持一致。这些数据为我们正在进行的针对LVRS手术风险高的重度肺气肿患者的立体定向消融减容（SAVR）前瞻性试验提供了参考。
