Keffer Stephen, Guy Christopher L, Weiss Elisabeth
Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia.
Adv Radiat Oncol. 2019 Aug 31;5(2):238-249. doi: 10.1016/j.adro.2019.08.010. eCollection 2020 Mar-Apr.
Fatal radiation pneumonitis is a rare event. In recent years, higher incidences of grade 5 pneumonitis have been reported. Based on 3 cases in our clinic, a literature review was performed to assess specific clinical features and risk factors for fatal pneumonitis.
Three patients with nonsmall cell lung cancer were treated with conventionally fractionated radiation therapy, 2 with volumetric modulated arc therapy and one with intensity modulated radiation therapy. All 3 patients had high volumes of 5 Gy in the total lung and contralateral lungs. Patients died of pneumonitis between 2 and 5 months after the end of radiation therapy. A literature review focused on grade 5 pneumonitis was performed for conventionally fractioned and stereotactic radiation therapy for lung cancer.
Patients with grade 5 pneumonitis develop symptoms sooner than lower grade pneumonitis. Symptoms often do not respond to steroid treatment or return after steroid taper. Imaging features extend beyond the high dose area and involve the contralateral lung. Dosimetric risk factors include both low dose and high dose lung volumes. For patients undergoing stereotactic radiation therapy interstitial lung disease has been described as a risk factor.
Despite decades of investigating radiation pneumonitis, the question of the optimum dose distribution in the lung, a large dose to a small volume versus a small dose to a large volume, is still unresolved. When both low and high dose lung volume constraints are followed, the risk for grade 5 pneumonitis has been shown to be low even with intensity modulated radiation therapy and concurrent chemotherapy. In addition to dose factors, underlying clinical and radiographic parameters play an important role for the development of grade 5 pneumonitis.
致命性放射性肺炎是一种罕见事件。近年来，5级肺炎的发病率有上升报道。基于我们诊所的3例病例，进行了文献综述以评估致命性肺炎的特定临床特征和危险因素。
3例非小细胞肺癌患者接受了常规分割放射治疗，2例接受容积调强弧形治疗，1例接受调强放射治疗。所有3例患者全肺和对侧肺接受5 Gy照射的体积均较大。患者在放射治疗结束后2至5个月死于肺炎。针对肺癌的常规分割和立体定向放射治疗，进行了一项聚焦于5级肺炎的文献综述。
5级肺炎患者比低级别肺炎患者出现症状的时间更早。症状通常对类固醇治疗无反应或在类固醇减量后复发。影像学特征超出高剂量区域并累及对侧肺。剂量学危险因素包括低剂量和高剂量肺体积。对于接受立体定向放射治疗的患者，间质性肺病被描述为一个危险因素。
尽管对放射性肺炎进行了数十年的研究，但肺部最佳剂量分布的问题，即小体积大剂量与大体积小剂量的问题，仍未得到解决。当遵循低剂量和高剂量肺体积限制时，即使采用调强放射治疗和同步化疗，5级肺炎的风险也已显示较低。除剂量因素外，基础临床和影像学参数对5级肺炎的发生也起着重要作用。
