Strauss G M, Gleason R E, Sugarbaker D J
Division of Hematology-Oncology, Brigham & Women's Hospital, Boston 02115.
Chest. 1993 Apr;103(4 Suppl):337S-341S.
In the 1970s, three randomized trials, each involving approximately 10,000 male subjects, were carried out to determine the value of lung cancer screening in cigarette smokers. These studies have been widely interpreted as providing strong evidence that screening does not contribute to decreased death rates, and, accordingly, the American Cancer Society firmly recommends against lung cancer screening. No randomized trial, however, has evaluated screening for lung cancer in women, who currently comprise 39% of the lung cancer population. The trials performed at Memorial-Sloan Kettering and at Johns Hopkins were designed so that subjects were randomized to either a single screen (annual chest x-ray alone) or a dual screen (annual chest x-ray and every-4-month sputum cytology) group. While the results of both revealed no difference in mortality between the groups, these studies were designed to examine the value of sputum cytology, and no conclusion regarding the efficacy of chest x-rays can be inferred. In the Mayo Lung Project, patients were randomized to a screened group in which a chest x-ray and sputum cytology were obtained every 4 months or to a control group in which an annual chest x-ray and cytology were simply recommended. The results indicate that after 6 years, more lung cancers were detected among the 4,618 men in the screened group (206 cases, 4.46%) than in the 4,593 men in the control group (160 cases, 3.48%). The screened group showed a superiority over the control subjects in resectability rate (46% vs 32%) and 5-year survival (33% vs 15%). However, the number of cancer deaths was slightly greater in the screened (122) than in the control group (115), and, consequently, the mortality rates were not significantly different among the groups. An "overdiagnosis bias" has been suggested to account for the increased number of lung cancers detected in the screened vs the control population in the Mayo Lung Project. This explanation is statistically plausible, but, given the status of lung cancer as the most lethal of malignancies, is biologically unlikely. An alternative hypothesis is that chance alone might have accounted for the observed 0.98% difference in lung cancer detection rates. Were this the case, then 46 additional cases would have been detected in the control group had this chance event not occurred.(ABSTRACT TRUNCATED AT 400 WORDS)
20世纪70年代，开展了三项随机试验，每项试验约涉及10000名男性受试者，以确定对吸烟者进行肺癌筛查的价值。这些研究被广泛解读为提供了有力证据，表明筛查无助于降低死亡率，因此，美国癌症协会坚决反对肺癌筛查。然而，尚无随机试验评估过针对女性的肺癌筛查，而目前女性占肺癌患者总数的39%。纪念斯隆凯特琳癌症中心和约翰霍普金斯大学进行的试验设计为，将受试者随机分为单筛组（仅每年进行胸部X光检查）或双筛组（每年进行胸部X光检查并每4个月进行痰细胞学检查）。虽然两组结果均显示死亡率无差异，但这些研究旨在检验痰细胞学检查的价值，无法推断出关于胸部X光检查疗效的结论。在梅奥肺癌项目中，患者被随机分为筛查组，每4个月进行一次胸部X光检查和痰细胞学检查，或对照组，仅建议每年进行一次胸部X光检查和细胞学检查。结果表明，6年后，筛查组的4618名男性中检测出的肺癌病例（206例，4.46%）多于对照组的4593名男性（160例，3.48%）。筛查组在可切除率（46%对32%）和5年生存率（33%对15%）方面优于对照组。然而，筛查组的癌症死亡人数（122人）略多于对照组（115人），因此，两组的死亡率无显著差异。有人提出“过度诊断偏差”来解释梅奥肺癌项目中筛查组与对照组相比检测出的肺癌病例增加的情况。这种解释在统计学上似乎合理，但鉴于肺癌是最致命的恶性肿瘤这一情况，从生物学角度来看不太可能。另一种假设是，仅仅是偶然因素导致了观察到的肺癌检出率0.98%的差异。如果是这样的话，那么若没有这个偶然事件，对照组本应多检测出46例病例。（摘要截选至400字）
