Choi N C, Kanarek D J
Department of Radiation Oncology, Massachusetts General Hospital Cancer Centre, Boston 02114.
Lung Cancer. 1994 Mar;10 Suppl 1:S219-30. doi: 10.1016/0169-5002(94)91685-3.
Physiological changes in pulmonary function (PF) as a result of radiation therapy (RT) or radiation therapy plus chemotherapy (RT + CT) for unresectable lung cancer were evaluated in an ongoing prospective study and an attempt was also made to define a guideline which can be used to minimize adverse effect of RT on pulmonary function before RT is given. The study design consisted of: (a) standard overall pulmonary function test (PFT); (b) regional PFT, i.e. a quantitative analysis of regional distribution of ventilation, perfusion and volume using 13N and a positron camera before RT; and (c) follow-up studies of standard PFT every 6 months for 3 years after RT or RT + CT. Predicted post-RT PF prior to RT was calculated by a formula: predicted FEV1 after RT = FEV1 before RT x (1 - an average of the percent of ventilation and perfusion contributed by lung tissue within the RT treatment volume). A total of 267 patients with unresectable, but still potentially curable lung cancer by RT were entered into this study, and 135 patients who were free of recurrence underwent repeat studies. Loss of PF as a result of RT is closely related to the degree of PF reserve prior to RT. Patients with FEV1 > 50% of the predicted showed a statistically significant decrease in FEV1, FVC, MBC, peak expiratory flow rate and DLCO, i.e. a 22% loss of the initial value. Airway resistance was increased by 31%. Two-thirds of this group of patients showed a decrease in PF as predicted by the above formula. For patients with limited PF reserve defined by FEV1 < 50% of the predicted, the pattern of PF loss after RT was quite different. An improvement in PF although it was < or = 10%, contrary to the prediction, was noted in 50% of patients, and another 37% of patients showed a small decrease in PF (< or = 10% of the initial value). Only 13% of patients showed a loss of pulmonary function as predicted by regional PF data. Patients with a significant shift (> 10%) of ventilation and/or perfusion to the uninvolved side of the lung by centrally located primary tumor or involved lymph nodes showed an increase in PF in 60% of patients after RT, and another 20% of patients showed a minor decrease in PF (< 10% of the initial value). Only 20% of these patients showed a decrease in pulmonary function as predicted by regional PF data. Guidelines for minimizing adverse effect of RT on PF, which are based on the initial PF reserve and regional PF data, are presented.
在一项正在进行的前瞻性研究中，评估了因放射治疗（RT）或放射治疗加化疗（RT + CT）用于不可切除肺癌导致的肺功能（PF）生理变化，并且还尝试制定一个指南，该指南可用于在进行放疗前将放疗对肺功能的不良影响降至最低。研究设计包括：（a）标准的全肺功能测试（PFT）；（b）局部PFT，即放疗前使用13N和正电子相机对通气、灌注和容积的区域分布进行定量分析；以及（c）放疗或RT + CT后每6个月进行一次标准PFT的随访研究，为期3年。放疗前预测的放疗后PF通过以下公式计算：放疗后预测的FEV1 = 放疗前的FEV1×（1 - 放疗治疗体积内肺组织贡献的通气和灌注百分比的平均值）。共有267例不可切除但仍有可能通过放疗治愈的肺癌患者进入本研究，其中135例无复发的患者接受了重复研究。放疗导致的PF丧失与放疗前PF储备程度密切相关。FEV1 > 预测值50%的患者，其FEV1、FVC、MBC、呼气峰值流速和DLCO在统计学上有显著下降，即初始值丧失22%。气道阻力增加31%。该组三分之二的患者放疗后PF下降如上述公式所预测。对于FEV1 < 预测值50%定义为PF储备有限的患者，放疗后PF丧失模式有很大不同。50%的患者PF有所改善，尽管改善幅度≤10%，与预测相反，另有37%的患者PF有小幅下降（≤初始值的10%）。只有13%的患者肺功能丧失如局部PF数据所预测。基于初始PF储备和局部PF数据，提出了将放疗对PF不良影响降至最低的指南。
