A new study published Wednesday in the New England Journal of Medicine found CT scans may lower lung cancer death rates among heavy smokers by a factor of about one-quarter to one-third, adding to mounting evidence that the practice can detect the disease while it's still treatable.
Despite recent drug developments and declining smoking rates, lung cancer is still a leading cause of death worldwide. According to researchers, part of the reason so many patients die from lung cancer is because the disease is usually diagnosed in the later stages, when the cancer has already spread.
But previously, doctors have found that performing CT screenings can help catch the cancer earlier when it can still be cured by surgery and other treatments. One U.S. study published in 2011, which followed 56,000 participants, found performing CT scans on a group of smokers reduced lung-cancer deaths in the group by 20%, compared with X-rays.
The study led the U.S. Preventive Services Task Force in 2013 to recommend that people aged 55 to 80 who, on average, smoked a pack of cigarettes per day for 30 years within the last 15 years be screened annually.
In 2015, Medicare started covering the scans, but Medicare reimbursement for the practice remains low, according to U.S. News & World Report.
But despite the recommendations, not everyone is on board: a panel of advisors and other doctors said there was a lack of evidence supporting preventive CT scans, adding that there is a risk of false positives and complications of follow-up procedures with the scans. As a result, the practice has not yet been widely adopted.
Are CT scans effective?
For the new study, researchers from the University of Erasmus in the Netherlands set out to determine whether CT scans are effective in detecting lung cancer in its early stages. The study, which is the second-largest study to observe preventive lung cancer screening, according to the Wall Street Journal, followed more than 15,000 men and women ages 50 to 74 from the Netherlands and Belgium who were currently or had previously been heavy smokers, which the researchers defined as smoking the equivalent of half a pack of cigarettes per day for 30 years.
The subjects were randomly assigned to one of two groups:
- One that underwent CT screenings at baseline and then after one year, three years, and 5.5 years; and
- Another group that didn't have any screenings.
The researchers followed the subjects for at least 10 years. At the conclusion of the follow-up, the researchers found that death rates among participants who were screened for lung cancer were 24% lower than the control group for men and 33% lower than the control group for women.
The researchers determined the CT scans detected 59% of the lung cancers among the participants who were regularly screened. Additionally, cancers that were detected were usually diagnosed in earlier stages.
The Dutch trial also had a lower rate of false positive CT scans than the 2011 U.S. study. Of the 467 men that required further screenings, 203 lung cancers were detected. Overall, 1.2% of male participants received a false positive result.
Should more people be screened for lung cancer?
The study findings provide more substantial evidence that preventive CT scans are effective at reducing lung-cancer death rates among heavy smokers, according to researchers.
Harry de Koning, a professor of public health at Erasmus University Medical Center in the Netherlands and lead author on the trial, said that the fact that the researchers observed a lower rate of false positives than the 2011 study could help quell previous concern that the CT scans would result in unnecessary worry.
Andrea McKee—the chair of radiation oncology at Lahey Hospital & Medical Center, who wasn't involved in the study—said, "It's essentially confirming that CT lung screening is incredibly powerful at detecting early stage lung cancer." She added, "These patients can be cured, and that's something a lot of people don't get because lung cancer has been so deadly."
The American College of Radiology (ACR) in a statement praised the study and estimated that if CT scanning for lung cancer was implemented, screenings could prevent 30,000 to 60,000 deaths per year (Abbott, Wall Street Journal, 1/29; Holmes, U.S. News & World Report, 1/30).