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CT Screening for Lung Cancer
In an uncontrolled study of annual screening in high-risk patients, most cancers were detected at an early stage.
The International Early Lung Cancer Action Program (I-ELCAP) is an uncontrolled prospective study of annual lung cancer screening by spiral computed tomography. More than 31,000 people were enrolled from 1993 through 2005; all were at increased risk for lung cancer by virtue of smoking history or occupational exposures, and all were deemed fit to undergo thoracic surgery. Study centers were guided by protocols for evaluating abnormal lung nodules; these evaluations included biopsies or repeat scans at shorter intervals.
During a median follow-up of 40 months, lung cancer was diagnosed in 484 patients; 85% of the cancers were clinical stage I. Estimated 10-year survival was 80% for all patients with lung cancer, and 88% for those with stage I tumors.
Comment: Not surprisingly, these results show that CT screening detects early-stage lung cancers, many of which may be curable. However, the absence of a control group is a limitation of this study. Potential pitfalls of uncontrolled screening studies include lead-time bias (i.e., making an earlier diagnosis without necessarily improving outcome), and overdiagnosis bias (i.e., detection of lesions that are histologically malignant but clinically indolent and not likely to cause death). In addition, it will be important to see whether the estimated 10-year survival in this cohort will accurately reflect the actual 10-year survival. A large National Cancer Institute–sponsored randomized trial of lung cancer screening, comparing spiral CT with conventional chest x-ray, is underway.
— Allan S. Brett, MD
Published in Journal Watch General Medicine October 25, 2006
Citation(s):
The International Early Lung Cancer Action Program Investigators. Survival of patients with stage I lung cancer detected on CT screening. N Engl J Med 2006 Oct 26; 355:1763-71.
- Medline abstract (Free)
Unger M. A pause, progress, and reassessment in lung cancer screening. N Engl J Med 2006 Oct 26; 355:1822-4.
- Medline abstract (Free)
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