Chien Chun-Ru, Chen Tony Hsiu-Hsi
Institute of Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan.
Int J Cancer. 2008 Jun 1;122(11):2594-9. doi: 10.1002/ijc.23413.
This study aimed to estimate the mean sojourn time (MST) and sensitivity of asymptomatic lung cancer (ALC) detected by computed tomography (CT) or chest X-ray (CXR). Translation of early diagnosis into mortality reduction by 2 detection modalities and inter-screening interval was projected using a Markov model. On the basis of systematic literature review, data from 6 prospective CT screening studies were retrieved. The MST in association with the natural history of lung cancer depicted by a 3-state Markov model was estimated with a Bayesian approach. To project mortality reduction attributed to screening, the model was further extended to 5 health states for the inclusion of prognostic part. The analysis was run with a 10-year time horizon of follow-up, mimicking the Dutch-Belgian randomized lung cancer screening trial (NELSON). Screening for lung cancer with CT had high sensitivity (median: 97%) and may advance 1 year earlier than CXR in detecting ALC. By simulating the scenario similar to NELSON study, CT screen may gain an extra of 0.019 year of life expectancy per person, yields 15% mortality reduction (relative risk (RR): 0.85, 95% confidence interval [95%CI: (0.58-1.01)]. Approximate 23% [RR: 0.77, 95%CI: (0.43-0.98)] mortality reduction would be achieved by annual CT screening program. The mortality findings in conjunction with higher sensitivity and shorter MST estimate given data on prevalent and incident (2nd) screen may provide a tentative evidence, suggesting that annual CT screening may be required in order to be effective in reducing mortality before the results of randomized controlled studies available.
本研究旨在估计通过计算机断层扫描（CT）或胸部X线（CXR）检测到的无症状肺癌（ALC）的平均停留时间（MST）和敏感度。使用马尔可夫模型预测了通过两种检测方式实现早期诊断从而降低死亡率以及筛查间隔时间。基于系统的文献综述，检索了6项前瞻性CT筛查研究的数据。采用贝叶斯方法估计了与三状态马尔可夫模型所描述的肺癌自然史相关的MST。为了预测筛查导致的死亡率降低情况，该模型进一步扩展到5种健康状态以纳入预后部分。分析在10年的随访时间范围内进行，模拟了荷兰 - 比利时肺癌随机筛查试验（NELSON）。CT筛查肺癌具有较高的敏感度（中位数：97%），并且在检测ALC方面可能比CXR提前1年。通过模拟与NELSON研究相似的情景，CT筛查每人可能额外获得0.019年的预期寿命，死亡率降低15%（相对风险（RR）：0.85，95%置信区间[95%CI：（0.58 - 1.01）]）。年度CT筛查计划将实现约23%[RR：0.77，95%CI：（0.43 - 0.98）]的死亡率降低。结合关于现患和新发病例（第二次）筛查的数据得出的死亡率结果、更高的敏感度以及更短的MST估计，可能提供了初步证据，表明在随机对照研究结果出来之前，可能需要进行年度CT筛查才能有效降低死亡率。
