Strauss G M, Gleason R E, Sugarbaker D J
Division of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
Chest. 1995 Jun;107(6 Suppl):270S-279S. doi: 10.1378/chest.107.6_supplement.270s.
It is believed that population-based screening for cancer should be advocated only when screening reduces disease-specific mortality. Four randomized controlled studies on lung cancer screening have been conducted in male cigarette smokers, and none has demonstrated reduced mortality. Accordingly, no organization that formulates screening policy advocates any specific early detection strategies for lung cancer. Yet, despite this public policy against screening, there is considerable evidence that chest x-ray screening is associated with earlier detection and improved survival. Two randomized trials, the Memorial Sloan-Kettering and Johns Hopkins Lung Projects, were specifically designed to evaluate the effectiveness of sputum cytologic study. Both evaluated the efficacy of the addition of sputum cytologic studies to annual chest radiographs, and both demonstrated that cytologic study did not favorably influence outcome. All individuals in experimental and control groups in both studies had annual chest radiographs. Because survival rates observed in both studies were about three times higher than predicted, based either on the National Cancer Institute's Surveillance Epidemiology and End Results database or based on the American Cancer Society's annual Cancer Statistics, raises the possibility that the periodic chest radiographs performed in all patients in both studies contributed to an improved outcome. In the Mayo Lung Project and in the Czechoslovak study on lung cancer screening, the experimental groups underwent a program of relatively intensive and regular rescreening with chest radiographs and sputum cytologic study, while the control groups underwent either less-frequent rescreening or no rescreening. In both studies, the screened groups achieved meaningful improvements in stage distribution, resectability, and survival. However, increases in cumulative incidence of lung cancer in the experimental group in both studies (which in the Mayo Lung Project reached statistical significance) prevented significant improvements in survival from translating into corresponding reductions in mortality. The possibility that screening may be associated with lung cancer "overdiagnosis" has been widely postulated to account for higher survival and incidence rates and equivalent mortality rates. However, analysis of autopsy information and of disease outcome in individuals with screen-detected early stage lung cancer who do not undergo surgical resection strongly supports the conclusion that screening does not lead to overdiagnosis of lung cancer. Similarly, lead-time and length bias do not adequately account for the differences in cumulative incidence observed in the Mayo and Czech studies.(ABSTRACT TRUNCATED AT 400 WORDS)
人们认为，只有当筛查能降低疾病特异性死亡率时，才应提倡基于人群的癌症筛查。针对男性吸烟者进行了四项肺癌筛查的随机对照研究，但无一显示出死亡率降低。因此，没有任何制定筛查政策的组织提倡任何特定的肺癌早期检测策略。然而，尽管有这项反对筛查的公共政策，但有大量证据表明胸部X光筛查与更早检测及改善生存率相关。两项随机试验，即纪念斯隆凯特琳癌症中心和约翰霍普金斯肺癌项目，专门设计用于评估痰细胞学研究的有效性。两者都评估了在年度胸部X光片基础上加做痰细胞学研究的疗效，且两者都表明细胞学研究对结果没有产生有利影响。两项研究的实验组和对照组所有个体都进行了年度胸部X光检查。由于两项研究中观察到的生存率比基于美国国立癌症研究所的监测、流行病学和最终结果数据库或基于美国癌症协会的年度癌症统计数据所预测的高出约三倍，这增加了两项研究中所有患者定期进行的胸部X光检查有助于改善结果的可能性。在梅奥肺癌项目和捷克斯洛伐克肺癌筛查研究中，实验组接受了相对密集且定期的胸部X光片和痰细胞学复查计划，而对照组复查频率较低或不进行复查。在两项研究中，筛查组在分期分布、可切除性和生存率方面都有显著改善。然而，两项研究中实验组肺癌累积发病率的增加（在梅奥肺癌项目中达到统计学显著性）使得生存率的显著提高未能转化为相应的死亡率降低。筛查可能与肺癌“过度诊断”相关的可能性已被广泛推测，以解释较高的生存率和发病率以及相同的死亡率。然而，对尸检信息以及未接受手术切除的筛查发现的早期肺癌个体的疾病结局分析有力地支持了筛查不会导致肺癌过度诊断的结论。同样，领先时间偏差和病程长短偏差也无法充分解释梅奥和捷克研究中观察到的累积发病率差异。（摘要截取自400字）
