ATS 2013：每年CT筛查可降低吸烟人群的肺癌死亡率

在线发表于2013年5月23日《新英格兰医学杂志》的一项研究显示，对于美国老年烟民或有重度吸烟史的人群，每年行CT筛查可减少相关死亡率。明尼苏达大学公共卫生学院环境卫生学部的Timothy R. Church博士及其同事称，全国肺癌筛查试验(NLST)的第一轮筛查结果显示，3年中，每年小剂量螺旋CT可比常规胸部X线检查发现明显更多的早期肺癌。

他们补充道，在真实的临床情境设定中，“美国有丰富的CT筛查经验的中心已经成功地使肺癌死亡率有所降低”。这些发现在线发表并同时在美国胸科学会(ATS)2013年会上发布。

研究的第一轮筛查共纳入53,454名年龄为55~74岁的无症状男女性。所有受试者均有至少30包/年的吸烟史，目前吸烟或戒烟不足15年。研究招募的受试者来自全美33家医院，经随机分组分别每年接受小剂量螺旋CT(n=26,722)或胸部X线检查(n=26,732)以筛查肺癌，周期为3年。首次筛查之前即被发现已罹患肺癌的8名受试者被排除在本项研究之外。

结果显示，小剂量CT扫描组的筛查结果阳性受试者比例为27.3%，显著高于胸部X线检查组的9.2%。两组被诊断为肺癌的受试者分别为1.1%和0.7%。在CT组中，发生肺癌的受试者92.5%有阳性的筛查结果(真阳性结果)，6.2%筛查结果为阴性(假阴性结果)，其余患者没有接受预定的筛查访视。在胸部X线检查组中，发生肺癌的受试者71.6%获得了真阳性筛查结果，25.8%得到了假阴性结果，其余患者没有接受预定的筛查。

Church医生及其同事说，因此，肺部CT的敏感性和特异性分别为93.8%和73.4%，而胸部X线检查的敏感性和特异性分别为73.5%和91.3%(N. Engl. J. Med. 2013 [doi:10.1056/NEJMoa1209120])。研究者称，“与胸部X线检查组相比，小剂量CT扫描组中有更多的细支气管肺泡癌(8例vs. 38例)和腺癌(71例vs. 123例)发生，但两组在其他组织学特征方面均相似。”在检出癌症数量方面两组之间的差异，几乎完全是由CT筛查明显更可能检测出早期肿瘤(ⅠA期)造成的。而对于更晚期的恶性肿瘤，CT筛查与胸部X线检查的检出率非常接近。

该项研究由国立癌症研究所赞助。无利益冲突报道。

Results of initial low-dose computed tomographic screening for lung cancer.
BACKGROUND
Lung cancer is the largest contributor to mortality from cancer. The National Lung Screening Trial (NLST) showed that screening with low-dose helical computed tomography (CT) rather than with chest radiography reduced mortality from lung cancer. We describe the screening, diagnosis, and limited treatment results from the initial round of screening in the NLST to inform and improve lung-cancer-screening programs.
METHODS
At 33 U.S. centers, from August 2002 through April 2004, we enrolled asymptomatic participants, 55 to 74 years of age, with a history of at least 30 pack-years of smoking. The participants were randomly assigned to undergo annual screening, with the use of either low-dose CT or chest radiography, for 3 years. Nodules or other suspicious findings were classified as positive results. This article reports findings from the initial screening examination.
RESULTS
A total of 53,439 eligible participants were randomly assigned to a study group (26,715 to low-dose CT and 26,724 to chest radiography); 26,309 participants (98.5%) and 26,035 (97.4%), respectively, underwent screening. A total of 7191 participants (27.3%) in the low-dose CT group and 2387 (9.2%) in the radiography group had a positive screening result; in the respective groups, 6369 participants (90.4%) and 2176 (92.7%) had at least one follow-up diagnostic procedure, including imaging in 5717 (81.1%) and 2010 (85.6%) and surgery in 297 (4.2%) and 121 (5.2%). Lung cancer was diagnosed in 292 participants (1.1%) in the low-dose CT group versus 190 (0.7%) in the radiography group (stage 1 in 158 vs. 70 participants and stage IIB to IV in 120 vs. 112). Sensitivity and specificity were 93.8% and 73.4% for low-dose CT and 73.5% and 91.3% for chest radiography, respectively.
CONCLUSIONS
The NLST initial screening results are consistent with the existing literature on screening by means of low-dose CT and chest radiography, suggesting that a reduction in mortality from lung cancer is achievable at U.S. screening centers that have staff experienced in chest CT. (Funded by the National Cancer Institute; NLST ClinicalTrials.gov number, NCT00047385.).