Computed tomography in screening for lung cancer

Findings by SBU Alert

Version: 2

Technology and target group

Approximately 2 800 new cases of cancer in the lungs and respiratory tract are diagnosed annually in Sweden. By the time it is diagnosed, the cancer has usually spread in the body, and the 5-year survival rate following diagnosis is approximately 10 percent. If cancer could be detected at an early stage, the hypothesis is that it would substantially improve the prognosis. Detecting lung cancer at an early, asymptomatic stage requires targeted screening. Earlier attempts to use chest radiography in early detection of lung cancer have not lowered the mortality rate from the disease. The development of spiral computed tomography (CT) and the use of lower radiation doses have, however, renewed the interest in screening. Smoking is the main cause of lung cancer. It has been estimated that it takes 20 to 30 years of smoking before lung cancer progresses to a symptomatic stage. A targeted screening program including all those who are or have been daily smokers, and are older than 45 years of age, would comprise 600 000 to 900 000 individuals annually in Sweden.

Patient benefit

Scientific studies have not confirmed that early detection of lung cancer leads to a reduction in mortality from the disease. As with assessments of screening for other types of cancer, eg, breast cancer, large, long-term, randomized trials would be required to answer this question. Six assessments, with major differences in design, have investigated the effectiveness of low-dose spiral CT in detecting early lung cancer. Lesions that led to followup examinations were detected in 5 percent to 69 percent. Between 0.4 percent and 2.7 percent of those screened were diagnosed as having lung cancer. The positive predictive value ranged between 2.8 percent and 11.6 percent. Two of the studies compared CT with chest radiography, and both studies showed that more tumors were detected with computed tomography. Most of the detected tumors were small (stage I).

Economic aspects

Detecting a single case of cancer at an early stage requires examination of a large number of people. This would suggest high costs for a screening program. Since the benefits of early detection have not been determined, model studies are the only way to estimate the cost effectiveness of the method.

Ethical aspects

Screening for lung cancer requires examination of a large number of healthy individuals in order to detect disease in, and offer treatment to, a few. Therefore, one must carefully weigh the advantages and disadvantages. Beyond subjecting patients to anxiety and time sacrificed in conjunction with the examination, the use of radiation involves some risk for induction of cancer. Also, a number of patients will be subjected to unnecessary invasive procedures due to false-positive test results.

Scientific evidence

Currently, there is good* scientific documentation of the capacity for low-dose CT to detect lung cancer at an early stage. There is no* scientific documentation to show how mortality would be affected by an organized program using low-dose CT for early detection of lung cancer. There is poor* documentation on the cost effectiveness of the method.

Before considering the appropriateness of routine screening for lung cancer, a positive effect on mortality must be demonstrated by large, controlled trials of screening programs.

*This assessment by SBU Alert uses a 4-point scale to grade the quality and evidence of the scientific documentation. The grades indicate: (1) good, (2) moderate, (3) poor, or (4) no scientific evidence on the subject.

This summary is based on a report prepared at SBU in collaboration with Ulf Tylén, Professor, Department of Radiology, Sahlgrenska Academy at Göteborg University, Sahlgrenska University Hospital, Göteborg. It has been reviewed by Bengt Bergman, Associate Professor, Pulmonary Medicine and Allergology, Sahlgrenska University Hospital, Göteborg.

Alert is a joint effort by the Swedish Council on Technology Assessment in Health Care (SBU), the Medical Products Agency, the National Board of Health and Welfare, and the Federation of Swedish County Councils.

References

1. Chirikos TN, Hazelton T, Tockman M, Clark R. Screening for lung cancer with CT: a preliminary cost-effectiveness analysis. Chest 2002;121(5):1507-14.
2. Diederich S, Lenzen H. Radiation exposure associated with imaging of the chest: comparison of different radiographic and computed tomography techniques. Cancer 2000;89(11 Suppl):2457-60. Review.
3. Diederich S, Wormanns D, Semik M, Thomas M, Lenzen H, Roos N, Heindel W. Screening for early lung cancer with low-dose spiral CT: prevalence in 817 asymptomatic smokers. Radiology 2002;222(3):773-81.
4. Gilljam H. Screening för lungcancer – dyrt och ineffektivt. Läkartidningen 2001;98(24):2952.
5. Henschke CI, McCauley DI, Yankelevitz DF, Naidich DP, McGuiness G, Miettinen OS et al. Early Lung Cancer Action Project: overall design and findings from baseline screening. Lancet 1999;354(9173):99-105.
6. Henschke CI, Naidich DP, Yankelevitz DF, McGuiness G, McCauley DI, Smith JP, Libby D et al. Early lung cancer action project: initial findings on repeat screenings. Cancer 2001;92(1):153-9.
7. ICRP. Recommendations of the International Commission on Radiation Protection (Publication 60). Oxford: Pergamon Press; 1991.
8. Kaneko M, Eguchi K, Ohmatsu H, Kakinuma R, Naruke T, Suemasu K et al. Peripheral lung cancer: screening and detection with low-dose spiral CT versus radiography. Radiology 1996;201(3):798-802.
9. Kakinuma R, Ohmatsu H, Kaneko M, Eguchi K, Naruke T, Nagai K et al. Detection failures in spiral CT screening for lung cancer: analysis of CT findings. Radiology 1999;212(1):61-6.
10. Manser RL, Irving LB, Stone C, Byrnes G, Abramson M, Campbell D. Screening for lung cancer (Cochrane Review). In: The Cochrane Library, Issue 3, 2002. Oxford: Update software.
11. Marshall D, Simpson KN, Earle CC, Chu C-W. Economic decision analysis model of screening for lung cancer. Eur J Cancer 2001;37(14):1759-67.
12. Mulshine JL, Henschke CI. Prospects for lung-cancer screening. Lancet 2000;355(9204):592-3.
13. Nawa T, Nakagawa T, Kusano S, Kawasaki Y, Sugawara Y, Nakata H. Lung cancer screening using low-dose spiral CT: results of baseline and 1-year follow-up studies. Chest 2002;122(1):15-20.
14. Patz EF Jr, Rossi S, Harpole DH Jr, Herndon JE, Goodman PC. Correlation of tumor size and survival in patients with stage IA non-small cell lung cancer. Chest 2000;117(6):1568-71.
15. Phillips M, Gleeson K, Hughes JM, Greenberg J, Cataneo RN, Baker L et al. Volatile organic compounds in breath as markers of lung cancer: a cross-sectional study. Lancet 1999;353(9168):1930-3.
16. Sone S, Takashima S, Li F, Yang Z, Honda T, Maruyama Y et al. Mass screening for lung cancer with mobile spiral computed tomography scanner. Lancet 1998;351(9111):1242-5.
17. Sone S, Li F, Yang ZG, Honda T, Maruyama Y, Takashima S et al. Results of three-year mass screening programme for lung cancer using mobile low-dose spiral computed tomography scanner. Br J Cancer 2001;84(1):25-32.
18. Swensen SJ, Jett JR, Sloan JA, Midthun DE, Hartman TE, Sykes AM et al. Screening for lung cancer with low-dose spiral computed tomography. Am J Respir Crit Care Med 2002;165(4):508-13.
19. Yankelevitz DF, Reeves AP, Kostis WJ, Zhao B, Henschke CI. Small pulmonary nodules: volumetrically determined growth rates based on CT evaluation. Radiology 2000;217(1):251-6.
    
    New references in update May 27, 2003
20. Mahadevia PJ, Fleisher LA, Frick KD, Eng J, Goodman SN, Powe NR. Lung cancer screening with helical computed tomography in older adult smokers: a decision and cost-effectiveness analysis. JAMA 2003;289(3):313-22.
21. Swensen SJ, Jett JR, Hartman TE, Midthun DE, Sloan JA, Sykes AM et al.
    Lung cancer screening with CT: Mayo Clinic experience. Radiology 2003;226(3):756-61.
22. http://www.cancer.gov/NLST