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    Heavy smokers should get a low-dose chest CT every year

    • High value
    • Evidence A
    • Buys life
    • For: Age 35+
    • Costs a little
    • Takes minutes
    • No willpower

    In plain words

    Eligible heavy smokers who get a low-dose CT every year have a 20% lower chance of dying of lung cancer than those who get only a chest X-ray, and a 6.7% lower chance of dying overall. The price is follow-up testing after a suspicious result, and the worry during that time.

    Cost

    One scan costs 200 to 400 CNY and takes 10 minutes. Also count the follow-up after a false alarm, and the worry during that time.

    What you get

    The U.S. NLST randomized trial enrolled 53,454 people, all aged 55 to 74, with a smoking history of 30 pack-years or more and who had quit no more than 15 years earlier. A pack-year is a unit for smoking amount: one pack a day for one year is one pack-year. The result: people who had a low-dose CT had a 20.0% relative reduction in lung cancer death compared with people who had only a chest X-ray (95% CI 6.8 to 26.7, the plausible range). Overall mortality fell 6.7% in relative terms (95% CI 1.2 to 13.6). Each person was screened three years in a row; across the three rounds, 24.2% of low-dose CT results were suspicious. Of the suspicious results, 96.4% were false alarms (false positives)

    Notes

    This applies only to high-risk smokers. In the same trial, across the three rounds of low-dose CT, 24.2% of the results were suspicious, and 96.4% of those turned out to be false alarms (false positives). Nonsmokers were not in this trial, so it cannot answer whether testing helps them.

    Evidence grade
    A : Specific numbers from meta-analyses, large cohorts or randomized trials; for law and policy, the statute or official text.
    Sources
    1. National Lung Screening Trial Research Team (2011). Reduced Lung-Cancer Mortality with Low-Dose Computed Tomographic Screening. New England Journal of Medicine: "The rate of positive screening tests was 24.2% with low-dose CT and 6.9% with radiography over all three rounds. A total of 96.4% of the positive screening results in the low-dose CT group and 94.5% in the radiography group were false positive results." https://doi.org/10.1056/NEJMoa1102873

    Mentioned in

    Translated from the Chinese original. Original book, section 1, tip 24. This section is about health and medicines. It is general information, not a substitute for a doctor’s diagnosis or prescription. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer