Screening people at high risk for lung cancer saves lives, a large clinical trial recently confirmed. Yet another study found that few of the people in the U.S. for whom the screening is recommended are getting it.
The trial, published in the New England Journal of Medicine in February 2020, included 13,195 men and 2,594 women, ages 50 to 74, all current or former heavy smokers. Half were randomly assigned to undergo four rounds of low-dose chest CT scans over 5.5 years. The other half got no screenings (the control group).
Over 10 years of follow-up, the rate of lung cancer deaths was 24 percent lower among men in the screening group than men in the non-screening group (156 deaths in the screening group and 206 in the control group). Among the women, the reduction was even greater—but the result did not reach statistical significance, possibly because the number of women with lung cancer included in the analysis was low.
CT scans are able to detect lung cancer early, when it’s at a more treatable stage, which is why they reduce mortality. Since 2013, the U.S. Preventive Services Task Force (USPSTF) has recommended annual lung scans for people ages 55 to 80 who currently smoke or quit within the past 15 years and who have at least a 30 “pack-year” history of smoking (for example, smoking one pack a day for 30 years or two packs a day for 15 years). The recommendations were based on a landmark federal study in 2011, which found that annual low-dose CT scanning for three years cut lung cancer deaths by 20 percent in more than 53,000 high-risk adults.
Because younger people and lighter smokers are at lower risk for lung cancer, the benefits of screening them don’t outweigh the downsides, which include the risk of false positive results and exposure to radiation, the USPSTF says.
Demand still down
Even as evidence supporting lung scans accumulates, a CDC report, also released in February 2020, shows that a large majority of the people in the U.S. who are candidates for annual scans aren’t getting them. The researchers analyzed data from more than 85,000 adults in 10 states who were surveyed by phone in 2017. (The states were Florida, Georgia, Kansas, Maine, Maryland, Missouri, Nevada, Oklahoma, Vermont, and Wyoming.)
Of the current or former smokers who met USPSTF criteria for screening, only one in eight (12.5 percent) had undergone a lung scan in the previous 12 months. This is a much lower rate than for other nationally recommended screening tests, namely mammograms and colonoscopies—though it represents an improvement over 2015, when only about 4 percent of people eligible for lung scans got them.
What’s more, a surprising number of smokers who didn’t meet the criteria for screening said they got scanned anyway: from about 4 percent to 9 percent across the 10 states, or 8 percent overall.
Words to the wise: Lung cancer is the leading cause of cancer death among men and women in the U.S., making up almost one-quarter of cancer deaths each year. More Americans die from lung cancer than from colorectal, breast, and prostate cancers combined. If you are unsure whether you should be screened, the National Cancer Institute offers an online tool. Another tool, from the University of Michigan, is available at ShouldIScreen.com. While the scans expose you to some radiation, it’s a very small amount (much less than in a standard CT scan). And the benefits for people who meet the screening criteria definitely outweigh this risk. The USPSTF says that screening should be stopped once a person has not smoked for 15 years or if he or she develops a health problem that substantially limits life expectancy or the ability to have lung surgery to remove cancer.
This article first appeared in the UC Berkeley Wellness Letter.