Early Lung Cancer Action Project
Abstract & commentary
Synopsis: The study concludes that low-dose CT scan improves the likelihood of detection of small noncalcified nodules, and thus lung cancer at an earlier and potentially more curable stage. The study also concludes that there is a similar malignant disease rate in patients with a solitary pulmonary nodule (SPN) as those with up to six noncalified nodules (NCN).
Source: Henschke CI, et al. Lancet 1999;354:99-105.
Lung cancer is the leading cancer cause of death in the United States in both men and women. The cure rate for all stages of lung cancer is 12%, while the five-year survival for stage I lung cancer is up to 70%. Based upon these results it is obvious that if lung cancers are found at an earlier and thus, resectable stage, there is a better chance for cure. Previous randomized trials evaluating chest radiographs (CXR) for screening have not shown any improvement in survival.
Henschke and colleagues designed a prospective trial to assess low-dose CT of the chest for detection of lung cancer in high-risk patients. The Early Lung Cancer Action Project (ELCAP) enrolled 1000 symptom-free volunteers who were at least 60 years old with a minimum 10-pack-a-year smoking history and who were medically fit to undergo surgery.
Henschke et al present the baseline data. All patients underwent CXR and low-dose CT of the chest at baseline. Results of the chest CT were classified as positive (1-6 NCN), negative (no NCN), or diffuse disease (> 6 NCN). Positive scans were followed up with high-resolution CT scans. Two hundred thirty-three patients (23%) had a positive low-dose CT, of which 202 had one or two nodules. Sixty-eight patients had a positive CXR, of which only 33 confirmed the nodule on chest CT. Twenty-seven of 233 (12%) of the positive low-dose CT had malignant disease. Seven of 68 (10%) of positive CXR had malignant disease. Thus, 20 of 27 malignant cases were missed by CXR. All 27 patients with noduleassociated malignancy were operable, 26 of 27 were resectable. Twenty-three of 27 were stage I, with 22 of 23 being stage IA. The overall malignant disease rate was 2.7%. The malignant disease rate in an SPN was 12% and was 11% in patients with 2 to 6 NCN.
COMMENT by David Ost, MD, & Suketu K. Shah, MD
Although lung cancer is the most common cause of cancer death in the United States, there is no currently recommended screening test for the disease. The reason for this is that previous tests did not detect the tumors at an early and more curative stage in a cost-effective manner. In the Mayo Lung Project, of the 59 tumors detected on standard CXR only 30 (51%) were considered resectable.1 The five-year survival for stage IA disease is 67% and for stage IB is 57%.2 This makes finding a good screening test for early-stage lung cancer an important issue. Henschke et al appear to have shown that low-dose CT in high-risk patients is a good tool at detecting early-stage lung cancers. This is especially true when compared with standard CXR, which missed 20 of 27 (74%) of the malignant nodules in this study and missed 18 of 22 stage IA cancers. The data from this study are only the baseline data and it will be interesting to see if on follow-up of the nodules that did not necessitate biopsy what percentage are malignant and how sensitive low-dose CT scanning is for lung cancer. This study does not address the cost-effectiveness of such an undertaking, but the group plans on including those data once the entire trial is completed. There is a question of whether these data can be applied to other centers. Sone et al detected only five lung cancers in 953 smokers (0.52%) in Japan.3 The five-fold discrepancy between studies may be a reflection of the different ethnicities and the lower age range of 40 years in the Japanese study.
References
1. Fontana RS, et al. Am Rev Respir Dis 1984;130:561-565.
2. Mountain CF. Chest 1997;111:1710-1717.
3. Sone S, et al. Lancet 1998;351:1242-1245.
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