Screening for Lung Cancer

Posted by • August 5th, 2011

The National Lung Screening Trial investigators report that persons undergoing three annual screening examinations with low-dose computed tomography had a 20% reduction in lung-cancer mortality as compared with those screened with annual chest radiography. The Original Article and accompanying editorial are available on

Even though the rate of heavy smoking continues to decline in the United States, 94 million smokers, half of whom are former smokers, remain at elevated risk for the disease, and lung cancer remains the leading cause of death from cancer in this country.

Clinical Pearls

What were the results of screening among patients in the low-dose computed tomography (CT) group?

During the screening phase of the trial, 39.1% of the participants in the low-dose CT group had at least one positive screening result. Across the three rounds, when a screening test was positive, 96.4% of the positive results in the low-dose CT group and 94.5% of those in the radiography group were false positive results.

According to the results of this study, how many participants would need to be screened to prevent one lung cancer death?

When only participants who underwent at least one screening test were included, there were 346 deaths from lung cancer among 26,455 participants in the low-dose CT group and 425 deaths among 26,232 participants in the radiography group. The number needed to screen with low-dose CT, as outlined in our protocol, to prevent one death from lung cancer was 320.

Figure 1. Cumulative Numbers of Lung Cancers and of Deaths from Lung Cancer.

Morning Report Questions

Q: What types of patients were eligible for screening in this study?

A: Eligible participants were between 55 and 74 years of age at the time of randomization, had a history of cigarette smoking of at least 30 pack-years, and, if former smokers, had quit within the previous 15 years.

Q: What type of cancers was discovered most frequently on low-dose CT radiography?

A: Low-dose CT screening identified a preponderance of adenocarcinomas, including bronchioloalveolar carcinomas. In both groups, many adenocarcinomas and squamous-cell carcinomas were detected at either stage I or stage II, although the stage distribution was more favorable in the low-dose CT group than in the radiography group. Small-cell lung cancers were, in general, not detected at early stages by either low-dose CT or radiography.

3 Responses to “Screening for Lung Cancer”

  1. The study suggest screening for smokers or X-smokers. However, screening should be performed on general population above age 55 of both sex.

    I wonder what will be the PPV on general population?

  2. Tarek safwat says:

    Very interesting, but mind you the size and cost of the procedure in an underdeveloped and poor country. Cost benefit to be calculated??

  3. mukesh s. paudel says:

    In countries where Chest CT is not easily available and with high prevalence Of TB, the false positives will be very high